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Karnataka 1st PUC Kannada Textbook Answers Sahitya Sanchalana Chapter 7 Akhanda Karnataka

Akhanda Karnataka Questions and Answers, Notes, Summary

You can Download Chapter 1 Introduction to Accounting Questions and Answers, Notes, 1st PUC Accountancy Question Bank with Answers Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.

Karnataka 1st PUC Accountancy Question Bank Chapter 1 Introduction to Accounting

1st PUC Accountancy Introduction to Accounting One Mark Questions and Answers

Question 1.
What is Book-keeping?
Answer:
Book-keeping is the art and science of recording in the books of account.
The monetary aspect of commerical and financial transactions.

Question 2.
Define Accounting.
Answer:
“The art of recording classifying and summarising in a significant manner and in terms of ‘ money transactions event which are, in part atleast, of a financial character and interpreting the results there of “American certificed public accountants”.

Question 3.
Write any two features of Accounting.
Answer:
Features of accounting are :

1. It is a process of recording business transactions.
2. Accounting is grouping the transactions according to their nature of heads.

Question 4.
Define Accountancy.
Answer:
According to Eric Kohler “Accountancy is the theory and practices of Accounting.

Question 5.
Mention the branches of accounting.
Answer:
Branches of accounting are :

1. Financial accounting.
2. Cost accounting.
3. Management accounting.

Question 6.
Mention the objectives of Accountancy.
Answer:

• To maintain the record of financial transactions of a business accurately.
• To ascertain the profit or loss made by business.
• To present the true and fair view of financial position.
• To know the amount due to creditors individually.

Question 7.
What are transactions?
Answer:
Business transactions means, any activity, dealing or event which has value measurable in terms of money related to business.

Question 8.
What is cash a transactions?
Answer:
Any business transaction which involves immediate payment or receipt of cash called cash transactions.

Question 9.
What is credit transactions?
Answer:
Any business transaction which involves postpone of payment or receipt to a future date called credit transactions.

Question 10.
What is capital?
Answer:
Capital represents the owner’s claim or share in the assets of the business. Amount invested by owner of business called capital.

Question 11.
Write the meaning of drawings.
Answer:
The amount of cash or any asset withdrawn by the owner of the business for his personal use or domestic use we called as drawings.

Question 12.
What are Assets?
Answer:
Assets are the properties or resources which are owned by the business entity.
Ex : Machinery, stock, goodwell, etc.

Question 13.
Who is a debtor?
Answer:
Debtor is a person who owes any amount to business. In other words, who purchase goods from business on credit basis is called debtors.

Question 14.
Who is a creditor?
Answer:
Creditor is a person to whom any sum of money is owed by business, other words the person who give benefits to business and amount payable, such person called creditors.

Question 15.
What are goods?
Answer:
The term goods includes all commodities, articles or products which are purchased for the purpose of re-sale.

Question 16.
What is stock?
Answer:
The goods purchased for sale, remain unsold called goods. It is a asset for the business.

Question 17.
Give the meaning of profit.
Answer:
It is an excess amount of revenues over the related cost or expenses, [profit = Revenue – expenditure].

Question 18.
Write the meaning of income and gain.
Answer:
Income: It refer to an amount received for sale of goods and service or for use of any rights belonging to business.
Gain: Increase in the value of assets or resources of business called gains.

Question 19.
What is Discount?
Answer:
Discount: Reducing the value of sales called discounting. Discounts are 2 types, Trade Discount and Cash Discount.

Question 20.
What is Vocher?
Answer:
Voucher: is the document which helps in reseeding business transactions.

Question 21.
Define Book-keeping.
Answer:
“Book keeping is the art of recording business transaction in a systematic manner”-Rosen.

Question 22.
Write any two features of Book-keeping.
Answer:
Features of book-keeping are :

1. It is the recording of only business transactions.
2. It is the recording of business transactions in terms of money. .
3. It is very systamatic and principled manner.

Question 23.
Question Write two objects of book-keeping.
Answer:
Objects of book of book-keeping are :

1. To have a permanent record of all business transactions.
2. To ascertain the net result of the business
3. To know the exact reasons for net profit or loss.
4. To know the progress of business from year to year
5. To minimise errors and frauds.

Question 24.
Differentiate between Book-keeping and Accounting.
Answer:

Book-keeping	Accounting
It is only a recording of business transaction.	It is a recording of, analysing, summarising of business transactions.
Book-keeping just maintaining business information.	Book-keeping is accounting, analysing and interprets the information.

Question 25.
Who is an accountant?
Answer:
An officer who is entrasted with the accounting function of the organisation called accountant.

Question 26.
Mention the two classification of Book-keeping.
Answer:
The two system of book-keeping are:

1. Single entry system of book-keeping.
2. Double-entry system of book-keeping.

Question 27.
Write the two advantages of single entry system.
Answer:

1. It is a simple method of recording transactions.
2. It is less costly when compared to double entry system.

Question 28.
Write any two disadvantages of single entry system.
Answer:

1. This system is an incomplete system of book-keeping.
2. This system is not supporting to prepare trial balance.

Question 29.
What is double entry system?
Answer:
The system of making two sides in the books of each contracting party for recording a transactions completely called double entry system.

Question 30.
Write the advantages of double entry system.
Answer:

• It provides a complete or full records of all transaction .
• It is a systematic and scientific manner of recording business transactions.

Question 31.
Write the disadvantages of double entry system.
Answer:

• Under this method number of books of accounts have to be maintained.
• It consumes more time and money.

Question 32.
Write the different types of business transactions.
Answer:
The business transactions can be classified as:

1. Cash transactions
2. Credit transactions
3. Barter transactions
4. Non-cash transactions

Question 33.
What is Entity?
Answer:
Entity means an area of economic interest of a particular industry or group of industries. Seperate books of accounts are kept for each entity.

Question 34.
What is intangible assets? Give examples.
Answer:
The assets which we cannot see and touch called intangible assets, example: Goodwell, Trade mark, patents, copy rights.

Question 35.
What is Liabilities?
Answer:
Liabilities are debts owed by the business entity to outsiders.
Example : Creditors, Bills payable, bank over draft, etc.

Question 36.
Write the meaning of solvent.
Answer:
Solvent is a person whose assets are equal or more than that of his liability.

Question 37.
Who is insolvent?
Answer:
Insolvent is a person whose assets are not sufficient to make payment of his liabilities infull.

Question 38.
What is purchases?
Answer:
Any articles, commodities or products bought for resale called purchses.

Question 39.
Give the meaning of entry.
Answer:
Entry: It means recording of business transactions in the books of Journal or subsidiary books.

Question 40.
What is Folio?
Answer:
Folio: It means the page number of books of accounts, it helps for referring the entry.

Question 41.
Write the meaning of carried down and Brought down.
Answer:
Carried down: It is the process of taking a balance of an account to the next period at the time of its closing. The short term is c/d.
Brought down : It is the process of bringing down the closing balance of the previous period to current year in the same account. It indicates opening balance. The short term is b/d.

Question 42.
Write the meaning of carry forward and brought forward.
Answer:
Carried forward: It is the process of taking the closing amount at the foot of the page of joumal/ledger etc. The short form is c/f.
Brought forward: It is the process of bringing forward the amount of previous page at the top of next page. The short term form is b/f.

Question 43.
Give the meaning of expenses and loss.
Answer:
Expenses: These are the amount spent for purchasing assets or material which is necessary for business.
Loss: Reduction in the value of assets or resources without any benefit called losses.

Question 44.
What is expenditure?
Answer:
Expenditure means a payment of cash or incurring a liability for acquiring assets, goods or service.

Question 45.
What is-Revenue?
Answer:
Revenue is the amount that adds to the capital. It represents cash generated by sale of goods or service offered.

Question 46.
What is accounting year?
Answer:
The accounts of a year are kept in a single set of books which contains 12 months, called accounting year. Generally it starts from 1st April and ends in 31st march of every year.

Question 47.
What is Accounting cycles?
Answer:
It refers to the flow of accounting data, in the course of accounting during the period of accounting.

Question 48.
What is accounting?
Answer:
Accounting is an art of recording, classifying, measuring and summarizing interms of money, of the business transaction.

Question 49.
Accounts is an art as well as.
Answer:
Science.

Question 50.
Mention one of the objective of accounting.
Answer:
One of the objective of accounting is
(a) Providing accounting information to its users.

Question 51.
Match the following.
(a) Internal users of accounting : Investors, govt. etc.
(b) External users of accounting : Management, share holders.
Answer:
(a) Internal users of accounting : Management, share holders.
(b) External users of accounting : Investors, govt etc.

Question 52.
Give examples for external users of accounting information.
Answer:
External accounting users are : Investors, suppliers / creditors government, customers etc.

Question 53.
Accounting information should be comparable. Do you agree?
Answer:
Yes. This statement is agreeable.

Question 54.
Accounting information should be comparable. Give reasons.
Answer:
Accounting information is always comparable reasons are :
(a) It helps in planning for future.
(b) It helps to compare different business organisation.

Question 55.
Shares is the example for…
Answer:
Revenue or income.

Question 56.
Commission received is a example for
(a) Revenue
(b) Cost
(c) Expenses
(d) Production
Answer:
(a) Revenue.

Question 57.
The primary use of accounting standards is
Answer:
Helps to maintain books in international market requirements.

Question 58.
Mention one feature of accounting.
Answer:
Feature of accounting is; Transactions are recorded in-terms of money.

Question 59.
What is profit?
Answer:
Profit is the excess of revenue over the expenses of a given period.

Question 60.
Give the meaning of gain.
Answer:
Gain refers to a revenue which not generated through regulate business activities.

Question 61.
Give examples for expenses.
Answer:
Rent, wages, salaries are examples for expenses.

Question 62.
Give one example for revenue.
Answer:
Sales, interest received, rent received are for examples.

Question 63.
Mention the different types of assets.
Answer:
The different types of assets are : Fixed assets and current assets.

Question 64.
Mention the different types of fixed assets.
Answer:
The different types of fixed assets are:

1. Tangible fixed assets
2. Intangible fixed assets.

Question 65.
Give one example for fixed assets.
Answer:
Fixed assets examples are : Land and building, plants and machinery furniture, vesicles etc.

Question 66.
Give one example for tangible assets.
Answer:
Examples for tangible for tangible assets.

Question 67.
Give one example for Intangible assets.
Answer:
Examples for intangible assets are : goodwill, patents, copyrights.

Question 68.
Give examples for current assets.
Answer:
Example for current assets are : Cash, stock, debtors, short term investment etc.

Question 69.
What is Fixed Assets?
Answer:
Fixed Assets are assets held on a longterm basis. Such as land Building Machinery etc. These assets are used for the normal operations of the business.

Question 70.
What is revenue?
Answer:
These are the amount of the business earned by selling its product (or) services to customer called revenue.

Question 71.
Give the meaning for examples.
Answer:
Costs incurred by a business in the process of earning revenue are called as Expenses. Example:- Depreciation, Rent, Wages, Salaries etc.

Question 72.
What is Capital?
Answer:
Amount invested by the owner to the business is known as capital.
Balance sheet / Equation = Capital = Assets – Liabilities.

1st PUC Accountancy Introduction to Accounting Two Marks Questions and Answers

Question 1.
Define Accounting.
Answer:
According to American Institute of Certified Public Accountants “Accounting is an art of recording, classifying & summarising in a significant manner & in-terms of money, transactions & events which are, in part at least of a financial character & interpreting the results thereof’.

Question 2.
What is end product of financial accounting?
Answer:
Balance sheet is the end product of financial accounting. It show the true financial positions of a business concern, that provides required informations like assets & liabilities of a business firm.

Question 3.
Enumerate main objectives of accounting.
Answer:
The main objectives of accounting are

1. Maintenance of Records of Business transaction.
2. Calculation of profit and Loss.
3. Depiction of financial position.
4. Providing Accounting information to its users.

Question 4.
Who are the users of Accounting information.
Answer:

• Internal users:- Management, who needs timely information for planning, controlling & decision making.
• External users:- Investors, Government, customers, competitors etc. obtain necessary information & rely on financial statement.

Question 5.
State the nature of accounting information required by long term lenders.
Answer:
Accounting information required by Longterm lenders are credit worthiness of the company & its ability to repay loans with Interest.

Question 6.
Who are External users of accounting information?
Answer:
External users of accounting informations are

a. Investors.
b. Suppliers & creditors
c. Customers
d. Government
e. Common man or society .
f. Lenders & financial institution.

Question 7.
Enumerate information needs to Management.
Answer:
Management needs timely information on cost of sales, profitability etc for planning, controlling & decision making.

Question 8.
Give any three Examples of revenues.
Answer:
Examples for revenues are ;
(a) Sales
(b) Commission received
(c) Interest received
(d) Dividend received.

Question 9.
Distinguish between Debtors & Creditors
Answer:
Debtors Creditors

Debtors	Creditors
(i) Debtors are persons and other entities who owe to an enterprise an amount for buying Goods & services on credit.	(i) Creditors are persons and other entities who have to be paid by an Enterprise goods & services on credit.
(ii) The total amount standing against such Persons (or) Entities on closing Date, is Show in the balance sheet as sundry Debtors on Assets side.	(ii) Total amount standing to the favour of such persons on closing Date, is shown in the Balance as sundry creditors on liability side.

Question 10.
Distinguish between profit & gain.
Answer:

Profit	Gain
(i) Profit is the Excess of revenue over the expenses of a given period, usually a year.	(i) Gain refers to a revenue which not generated through routine or regular business activities.
(ii) Profits increases the investment office owners	(ii) Gain increases the profit of an enterprises

Question 11.
Accounting information should be comparable. Do you agree with this statement. Give two reasons.
Answer:
Yes this Statement is agreeable.
The reasons are as follows:-
a. It helps in planning for the future.
b. It also useful in the areas of decision making in an organization.

Question 12.
If accounting information is not clearly presented, which of the qualitative characteristics of accounting is violated?
Answer:
If accounting information is not clearly presented, then the qualitative characteristics like comparability, reliability & understandability are violated.

Question 1.3.
The Role of accounting has changed over the period of time? Do you agree? Give reasons.
Answer:
The role of accounting is over changing. While in earlier times, accounting was merely concerned with recording the financial events i.e. record keeping activity. However, now a days, accounting is done with the rationale of not only maintaining records, but also providing information to various accounting users area.

Question 14.
With Example, Explain each of the following accounting term.
(a) Fixed Assets
(b) Revenue
(c) Expenses
(d) Short term liability
(e) Capital
Answer:
(a) Fixed Assets Fixed Assets are assets held on a longterm basis. Such as land Building Machinery etc. These assets are used for the normal operations of the business.
(b) Revenue These are the amount of the business earned by selling its product (or) services to customer called revenue.
Example Sales, Commission received, Rent received etc.
(c) Expenses:- costs incurred by a business in the process of earning revenue are called as . Expenses.
Example:- Depreciation, Rent, Wages, Salaries etc.
(d) Short term liability:- Short term liability are obligations that are payable within a period of one year.
Examples:- Creditors, Bills payable, etc.
(e) Capital:- Amount invested by the owner to the business is known as capital.
Balance sheet / Equation = Capital = Assets – Liabilities.
Example:- if, on a given date, the total Assets of a business are ?6,000 & the total liabilities of business are ?20,000 the excess of the total assets over total liabilities of the business (60,000 -20,000) ?40,000 will be owners capital.

Question 15.
Define revenues & expenses.
Answer:
According to American Accounting Association “Revenue is the monetary Expression of the aggregate of products (or) services transferred by the Enterprises to its customers during a period of time.”
According to Robert. N. Anthony “Expenses are the costs incurred in connection with the earnings of revenue”.

Question 16.
What is the primary reason for the business students & others to familiarize themselves with the accounting discipline?
Answer:
The reason for why business students & others should familiarize themselves with the accounting discipline are given below:-

• It helps in learning the various aspects of accounting.
• It helps in learning how to maintain books of accounts.
• It helps in learning how to summarise accounting information.

Question 17.
Give the meaning of expenses and loss.
Answer:
Expenses: These are the amount spent for purchasing assets or material which is necessary for business.
Loss: Reduction in the value of assets or resources without any benefit called losses.

Question 18.
What is expenditure?
Answer:
Expenditure means a payment of cash or incurring a liability for acquiring assets, goods or service.

Question 19.
What is Revenue?
Answer:
Revenue is the amount that adds to the capital. It represents cash generated by sale of goods or service offered.

1st PUC Accountancy Introduction to Accounting Six Marks Questions and Answers

Question 1:
Explain the factors, which necessitated systematic accounting?
Answer:
The factors that necessitated systematic accounting are given below:

a. Only financial transactions are recorded: Those events that are financial in nature are only recorded in the books of accounts. For example, salary of an employee is recorded in the books but not recorded educational qualification.

b. Transactions are recorded in monetary terms: Only those transactions which can be expressed in monetaiy terms are recorded in the books. For example, if a business has two buildings and four machines, then their monetary values is recorded in the books,
i. e. two buildings costing ? 20,000, four machines costing ? 8,00,000. Thus the total value of assets is ? 8,20,000.

c. Art of recording: Transactions are recorded in the order of their occurrence (Date, wire).

d. Classification of Transaction: Business transactions of similar nature are classified and posted under their respective accounts. For example, all the transactions relating to machinery will be posted in the Machinery Account.

e. Summarising of data: All business transactions are summarized in the form of Trial Balance, Trading Account, Profit and Loss Account and Balance Sheet that provides necessary information to various users.

f. Analysing and interpreting data – Systematic accounting records enable users to analyse and interpret the accounting data in a proper and appropriate manner. These accounting data and information are presented in the form of graphs, statements, charts, that leads to easy communication and understand ability by various users. Moreover, this facilitates in decision making and future predictions.

Question 2.
Describe the brief History of accounting.
Answer:
a. The history of accounting can be traced long back in civilization. Around 4000 B.C., in Babylonia and Egypt, payment of wages and taxes were recorded on clay tablets. As history claims that Egyptians kept the record of gold and valuables deposits and withdrawal from the treasuries. These records were reported on daily basis by the incharge of treasuries to the wazir, who used to forward the monthly reports to the king. Babylonia and Egypt used this method to rectify and remove errors, frauds and inefficiency from the records. Around 2000 B.C., China used sophisticated form of accounting.

In Greece, accounting was used to maintain total receipts and total payments and to balance government accounts.
In Rome, around 700 B.C., receipts and payments were recorded in daybook and were posted in the ledger at the end of the month.

b. In India, around twenty three centuries ago, Kautilya wrote the book Arthshastra, which describes how accounting records have to be maintained.

c. In 1494, Luca Pacioli wrote the book ‘Summa’ de Arithmetica Geometria Proportioniet Proportionality. In this, he explained the term debit and credit, which are used in accounting till date.

Question 3.
Explain the development and role of accounting.
Answer:
Development of accounting
In ancient times, around 4000 B.C., accounting was used for recording wages and salaries, deposits and withdrawals of valuable goods (such as gold and silver) from the treasures of the king. Afterwards, it was used to record the receipts and payments and balancing of government financial transactions.

During 1500 A. D., accounting was used by business firms for recording transactions related to business.
In 1800 A.D., accounting was used to record transactions and also to provide information to various users of financial data.

Role of accounting.
While in the earlier times accounting was merely concerned with recording the financial events (i.e. record-keeping activity); however, now-a-days, accounting is done with the rationale of not only maintaining records, but also providing an information system that provides important and relevant information to various accounting users. .

a. Substitute of memory : As, it is beyond human capabilities to remember each and every business transaction, so accounting plays an important role in recording these transactions in the book of accounts.
b. Assistance to management: Management uses accounting information for short term and long term planning of business activities and to control various costs and budgets.
c. Comparative study : In order to ascertain the performance of the business, accounting enables comparison of current year’s profit with that of previous years (intra-firm comparison) and also with other firms in the same business (inter-firm comparison).
d. Evidence in court: It acts as evidence that can be used or presented in the court, if any discrepancy arises in the future.

Question 4.
Define accounting and state its objectives.
Answer:
In 1970, American Institute of Certified Public Accountants changed the definition and stated, “The function of accounting is to provide quantitative information, primarily financial in nature, about economic entities, that is intended to be useful in making economic decisions.”

Objectives of Accounting:

a. Recording business transactions systematically: It is necessary to maintain systematic
records of every business transaction, as it is beyond human capacities to remember such large number of transactions. Skipping the record of any one of the transactions may lead to erroneous and faulty results. ,

b. Determining profit earned or loss incurred: In order to determine the net result at the end of an accounting period, we need to calculate profit or loss. For this purpose trading and profit and loss account are prepared. It gives information regarding how much of goods have, been purchased and sold, expenses incurred and amount earned during a year.

c. Ascertaining financial position of the firm: Ascertaining profit earned or loss incurred is not enough proprietor also interested in knowing the financial position of his/her firm, i.e. the value of the assets, amount of liabilities owed, net increase or decrease in his/her capital. This purpose is served by preparing the balance sheet that facilitates in ascertaining the true financial position of the business.

d. Assisting management: Systematic accounting helps the management in effective decision making, efficient control on cash management policies, preparing budget and forecasting, etc.

e. Assessing the progress of the business: Accounting helps in assessing the progress of business from year to year, as accounting facilitates the comparison both inter-firm as well as intra-firm.

f. Detecting and preventing frauds and errors: It is necessary to detect and prevent fraud and errors, mismanagement and wastage of the finance. Systematic recording helps in the easy detection and rectification of frauds, errors and inefficiencies, if any.

g. Communicating accounting information to various users: The important step in the accounting process is to communicate financial and accounting information to various users including both internal and external users like owners, management, government, labour, tax authorities, etc. This assists the users to understand and interpret the accounting data in a meaningful.

Question 5.
Describe the informational needs of external users.
Answer:
There are various external users of accounting who need accounting information for decision making, investment planning and to assess the financial position of the business. The various external users are given below.

a. Banks and other financial institutions: Banks provide finance in form of loans and advances to various businesses. Thus, they need information regarding liquidity, creditworthiness, solvency and profitability to advance loans.

b. Creditors: These are those individuals and organisations to whom a business owes money on account of credit purchases of goods and receiving services; hence, the creditors require information about credit worthiness of the business.

c. Investors and potential investors: They invest or plan to invest in the business. Hence, in order to assess the viability and prospectus of their investment, creditors need information about profitability and solvency of the business.

d. Tax authorities: They need information about sales, revenues, profit and taxable income in order to determine the levy various types of tax on the business.

e. Government: It needs information to determine national income, GDP, industrial growth, etc. The accounting information assist the government in the formulation of various policies measures and to address various economic problems like employment, poverty etc.

f. Researcher: Various research institutes like NGOs and other independent research institutions like CRISIL, stock exchanges, etc. undertake various research projects and the accounting information facilitates their research work.

g. Consumer: Every business tries to build up reputation in the eyes of consumers, which can be created by the supply of better quality products and post-sale services at reasonable and affordable prices. Business that has transparent financial records, assists the customers to know the correct cost of production and accordingly assess the degree of reasonability of the price charged by the business for its products and thus helps in repo building of the business.

h. Public: Public is keenly interested to know the proportion of the profit that the business spends on various public welfare schemes; for example, charitable hospitals, funding schools, etc. This information is also revealed by the profit and loss account and balance sheet of the business.

Question 6.
What do you mean by an asset? Explain the different types of assets.
Answer:
Any valuable thing that has monetary value, which is owned by a business, is its asset. In other words, assets are the monetary values of the properties or the legal rights that are owned by the business organisations.
The different types of assets are ;

a. Fixed Assets: These are those assets that are hold for the long term and increase the profit earning capacity and productive capacity of the business. These assets are not meant for sale, for example, land, building machinery etc.
b. Current Assets : Assets that can be easily converted into cash or cash equivalents are termed as current assets. These are required to run day to day’ business activities; for example, cash, debtors, stock, etc.
c. Tangible Assets : Assets that have physical existence, i.e., which can be seen and touched, are tangible assets; for example, car, furniture, buildings, etc.
d. Intangible Assets : Assets that cannot be seen or touched, i.e. those assets that do not have physical existence, are intangible assets; for example, goodwill, patents, trade mark, etc.
e. Liquid Assets : Assets that are kept either in cash or cash equivalents are regarded as liquid assets. These can be converted into cash in a very short period of time; for example, cash, bank, bills receivable, etc.
f. Fictitious Assets : These are the heavy revenue expenditures, the benefit of whose can be derived in more than one year. They represent loss or expense that are written off over a period of time.

Question 7.
Write the meaning of gain and profit. Distinguish between gain and profit.
Answer:
Profits: Excess of revenue over expense is known as profit. It is normally categorized into ’ gross profit or net profit. It increases the owner’s capital as it is added to the capital at the end of each accounting period.
For example: Goods costing ₹ 1,000 is sold at ₹ 1,200 then the sale proceeds of ₹ 1,200 is the revenue and 1,000 is the expense to generate this revenue. Hence, accounting profit of ₹ 200 (i.e. ₹ 1,200 – ₹ 1,000) is the difference between the revenue and expense that is earned by the business.

Gain: It arises from irregular activities or non-recurring transactions. In other words, a gain is a result of transactions that are incidental to the business, other than operating transactions. For example: an old machinery of book value ₹ 2,000 is sold at ₹ 2,500. Hence, the gain is ₹ 5,00 (i.e. ₹ 25,00 – ₹ 2,000). Here, the sale of the old machinery is an irregular activity; so, the difference is termed as gain. Thus, in other words the only difference between profit and gain is that profit is the excess of revenue over expense and gain arises from other than operating transactions.

	Profit	Gain
1.	Profit is derived from regular business regular business activity	Gain is derived from investment over on period of time not falling under regular business activity.
2.	It is return on capital employed.	It is return on investment
3.	Profit is the summation of total income less total expenses	Gain is the process received from the sale of fixed or financial assets.

Question 8.
Explain the qualitative characteristics of accounting information.
Answer:
The following are the qualitative characteristics of accounting information:

a. Reliability: It means that the user can rely on the accounting information. All accounting information is verifiable and can be verified from the source document (voucher), viz. cash memos, bills, etc. Hence, the available information should be free from any errors and unbiased.

b. Relevance: It means that essential and appropriate information should be easily and timely available and any irrelevant information should be avoided. The users of accounting information need relevant information for decision making, planning and’ predicting the future conditions.

c. Understandability: Accounting information should be presented in such a way that
every user is able to interpret the information without any difficulty in a meaningful and appropriate manner. ,

d. Comparability- It is the most important quality of accounting information. Comparability means accounting information of a current year can be comparable with that of the previous years. Comparability enables intra-firm and inter-firm comparison. This assists in assessing the outcomes of various policies and programmes adopted indifferent time horizons by the same or different businesses.

Question 9.
Describe the role of accounting in the modern world.
Answer:
The role of accounting has been changing over the period of time. In the modem world, the role of accounting is not only limited to record financial transactions but also to provide a basic framework for various decision making, providing relevant information to various users and assists in both short run and long run planning.

The role of accounting in the modem world is given below:

Assisting management: Management uses accounting information for short term and long term planning of business activities, to predict the future conditions, prepare budgets and various control measures.

Comparative study: In the modem world, accounting information helps us to know the performance of the business by comparing current year’s profit with that of the previous years and also with other firms in the same industry. .

Substitute of memory: In the modem world, every business incurs large number of transactions and it is beyond human capability to memorise each and every transaction. Hence, it is very necessary to record transactions in the books of accounts.

Information to end user: Accounting plays an important-role in recording, summarizing and providing relevant and reliable information to its users, in form of financial data that helps in decision making.

1st PUC Accountancy Introduction to Accounting Additional Questions and Answers

Question 1.
Write the advantages and disadvantages of book-keeping.
Answer:

	Book-keeping Advantages	Book-keeping Disadvantages
1.	It provide full information about all expenses and loss.	It gives only monetary transaction information.
2.	It is return on capital employed.	It is return on investment
3.	It helps to know the true financial position of business.	This recordings do not give exact information and timely information.
4.	It helps to know the progress of business from year to year.	Final accounts prepared under book-keeping do not provide timely information.
5.	It helps to know from whose money due and to whom due.	With the help of only book-keeping management can’t take decision and correct action cannot be possible.
6.	It keep control over the properties and activities of business.	Book-keeping depends on personal judgment.

Question 2.
Explain the features of accounting.
Answer:
The features / Natures of accounting are :

• Recording of business transaction as and when they occur in single book is the first feature of accounting.
• Classify or grouping of entries according to their nature in to appropriate heads of account.
• Accounting also involves summarising the transactions, classified in the ledger and financial position presentation.
• Accounting also analyse and interpret the recorded transactions.

Question 3.
Differentiate book-keeping and accounting. .
Answer:

	Book-keeping	Accounting
1.	It is an art of recording money transaction in a-set of books.	It is a process of designing the system of records of books of a/cs.
2.	It is a mechanical and routine Work.	It requires specialised knowledge and creative ability.
3.	Book-keeper is a clerk.	Accountant is a professionalist.
4.	Book-keeping creates a data base.	It process the finacial data and finds results and conclusion.
5.	It helps to know from whose money due and to whom due.	With the help of only book-keeping management can’t take decision and correct action cannot be possible.

Question 4.
Accounting is an art as well as science. Discuss.
Answer:Accounting is an art: art means application of knowledge to produce the desired result, accounting ivolves the designing of information system, record filing system, standardisation of forms and statements etc. The working of an accounting needs creative and active skills . and involvement of all staff.

Accounting is also science: A ‘Science’ means a systematic body of knowledge relating to universal phenomenon. It consists of concept theories, rules, and techniques developed by the process of rational thinking and spirit of enquiry, accounting is a social science..
So accounting is a applied science as well as art of recording a business transactions.

Question 5.
Write the objectives or advantages of accounting.
Answer:
The objectives or advantages of accounting are:

• To maintain the record of financial transactions of a business accurately.
• To ascertain the profit or loss made by business.
• To present the true and fair view of financial position.
• To know the amount due to creditors individually.
• To know the amount due from debtors to the business.
• To compute the tax liability of the concern.
• To supply the required financial information to the mangement it helps for decision making.

Question 6.
Explain the role or growth of accounting.
Answer:
The origin and growth of accounting can be summarised as follows:

• Accounting is said to be very old, as old as money.
• The present accounting is the result of constant innovations to the requirements of business activities.
• Accounting has developed to meet the emerging needs and requirements of fast developing society.
• “Arthashastra” the book written by Kautilya is the base or foundation for accounting.
• The present system of accounting based on the double entry system founded by pacilio in 1494 at Italy.
• Futher various publications were made and an important publications was that of edward jones in 1975 who invovated the concept of ‘Two Column journal’.

Question 7.
State the different terms in Accounting.
Answer:
Drawings: The amount of cash or any asset withdrawn by the owner of the business for his personal use or domestic use we called as drawings.

• Assets: are the properties or resources which are owned by the business entity.
  Ex: Machinery, stock, goodwell, etc.
  Liabilities are debts owed by the business entity to outsiders.
  Example: Creditors, Bills payable, bank over draft, etc.
• Debtor: is a person who owes any amount to business. In other words, who purchase goods from business on credit basis is called debtors.
• Creditor: is a person to whom any sum of money is owed by business. Other words the person who give benefits to business and amount payable, such person called creditors.
• Goods: The term goods includes all commodities, articles or products which are purchased for the purpose of re-sale.
• Purchases: Any articles, commodities or products bought for resale called purchases.
• Sales: Any goods purchase by customer called sales mean sale of goods and not the assets. Stock: The goods purchased for sale, remain unsold called goods. It is a asset for the business.
• Profit: The accounts of a year are kept in a single set of books which contains 12 months, called accounting year. Generally it starts from 1st April and ends in 31st march of every year.
  • Expenditure means a payment of cash or incurring a liability for acquiring assets, goods or service.
  • Revenue is the amount that adds to the capital. It represents cash generated by sale of goods or service offered.
• Discount: Reducing the value of sales called discounting. Discounts are 2 types, Trade Discount and Cash Discount.
• Voucher: is the document which, helps in reseeding business transactions.
• Income: It refer to an amount received for sale of goods and service or for use of any rights belonging to business.
• Gain: Increase in the value of assets or resources of business called gains.
  Capital represents the owner’s claim or share in the assets of the business. Amount invested by owner of business called capital.
• Entity: means an area of economic interest of a particular industry or group of industries. Separate books of accounts are kept for each entity

You can Download Chapter 13 Computerised Accounting System Questions and Answers, Notes, 1st PUC Accountancy Question Bank with Answers Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.

Karnataka 1st PUC Accountancy Question Bank Chapter 13 Computerised Accounting System

1st PUC Accountancy Computerised Accounting System One Mark Questions and Answers

Question 1.
What is computerised accounting system?
Answer:
It is an accounting information system that processes the financial transaction and events an per GAAP.

Question 2.
Expand GAAP
Answer:
Generally accepted accounting principles = GAAP.

Question 3.
Mention the elements computer system?
Answer:
Computer system elements are Hardware, Software people, procedure, data and connectivity.

Question 4.
What is Hardware?
Answer:
Hardware of computer includes – physical components like, keyboard, mouse, monitor, CPU etc. These are electronic and electromechanical components.

Question 5.
What is software or program of computer?
Answer:
A set of program, which is used to work with hardware is called its software.

Question 6.
What is firmware?
Answer:
A coded set of instructions stored in the form of circuits is called firmware.

Question 7.
Mention the different types of software.
Answer:
The different types of software are ;

1. Operating system
2. Utility program
3. Application software
4. Language processors
5. System software
6. Connectivity software.

Question 8.
What is procedure as a element of computer system?
Answer:
A procedure means a series of operations in a certain order or manner to achieve desire results.

Question 9.
Mention the different types of procedure in computer system.
Answer:
The different types of computer system procedures are:

1. HardWare – oriented
2. SoftWare – oriented
3. Internal procedure.

Question 10.
List out the capabilities of computer system.
Answer:
Capabilities of computer system are:

• Speed
• Accuracy
• Reliability
• Storage

Question 11.
List out any two limitations of computer system.
Answer:
The demerits or limitations of computer system are;

• Lack of common sense
• Lack of decision making
• Compulsory instructor.

Question 12.
Mention two features of computerised accounting system.
Answer:
The two features of computerised accounting system are :

1. Online input and storage of accounting data.
2. Grouping of ledger accounts is done in the beginning itself.
3. Quick reporting to management and various types of reports can be produce.
4. Invoices like purchase and sales can be prepared.

Question 13.
What is accounting information system?
Answer:
Accounting information system, identifies, collects, process and communicates economic information about an entity to a wide variety of users.

Question 14.
What is accounting report?
Answer:
Information supplied to meet a particular need of management is called report. It is helpful for management decision making.

Question 15.
List out the requisite of good accounting report.
Answer:
An accounting report must fulfill;

• Relevance
• Timeliness
• Accuracy
• Summarisation

1st PUC Accountancy Computerised Accounting System Six Marks Questions and Answers

Question 1.
State the four basic requirements of a Database Applications.
Answer:
The following are the four basic requirements of a Database Application:
a. Front-end Interface- It acts as an interactive connecting link between the user and the database oriented software through which the user communicates or interacts to the backend database.

b. Back-end Database- It is the data storage system that is hidden from the users. It responds to the requirement of the users to the extent the user is authorised to access.

c. Data Processing- It is a sequence of actions that are taken to transform the input data into useful information for taking various decisions.

d. Reporting System- It is an integrated set of objects that includes all the relevant information that constitutes a report.

Name the various categories of Accounting Package.
The Accounting Packages are classified into the following categories:
a. Ready-to-use or Readymade Software
b. Customised Software
c. Tailored or Tailor-made Software

List the various advantages of Computerised Accounting Systems.
The mentioned below are the various advantages of Computerised Accounting Systems:
a. Speed
b. Accuracy
c. Reliability
d. Up-to-Date Information
e. Real Time User Interface
f. Automated Document Production
g. Scalability
h. Legibility

Give two examples each of the organisations where ‘ready-to-use’, ‘customised’, and ‘tailored’ accounting packages respectively suitable to perform the accounting activity.

‘Ready-to-use’ accounting packages are basically used by the small-sized enterprises. For example, grocery stores, medical stores, etc.

On the other hand, ‘Customised’ accounting packages are basically used by the medium and large business. For example, shopping malls, hospitals, etc.

Whereas, ‘Tailored’ accounting packages are basically used by the geographically scattered businesses. For example, MNC’s, Communication Industries, etc.

Question 2.
Distinguish between ‘ready-to-use’ and ‘tailored’ accounting software.
Answer:

Basis of Difference	Ready-to-Use Accounting Software	Tailored Accounting Software
1. Nature of Business	This software is used in small and conventional businesses.	This software is used in large and typical businesses.
2. Adaptability	Its adaptability is very high.	Its adaptability is very specific and cannot be used by every business houses.
3. Linkage to other Information System	Its interface with the other information system is limited	Its interface with the other information system is unlimited
4. Number of Users	It has limited users.	It has huge number of users.
5. Installation and Maintenance Costs	The installation and maintenance cost is low.	The installation and maintenance cost is comparatively higher

Question 3.
Define a Computerised Accounting System. Distinguish between a Manual and Computerised Accounting Systems.
Answer:
Computerised Accounting Systems is based on the concept of database. It is an accounting information system that processes the financial transactions and events in accordance to the Generally Accepted Accounting Principles (GAAP) to produce reports as per the requirements of the users.

Manual Accounting	Computerised Accounting
1. As the data a recorded under manual accounting are visible.	As the data stored in computers are not visible.
2. The rail of events under manual accounting can be easily established	The rail of transactions (or) events cannot be established easily under computersied accounting.
3. The data recorded in manual accounting are not subjected to the risk of manipulation	The data recorded in computerised ac­counting system are subject to the risk of manipulation.
4. In manual accounting, accounting data cannot be adjusted to produce various special statement and reports	Under a computerised accounting system the accounting data can be easily adjusted to generate various special statement and reports.
5. The cost of preparing statement and report under manual accounting is high.	The cost of preparing statements and re­ports under computerised accounting is low
6. The reports prepared under manual accounting are mostly board and general purpose reports.	Under computerised accounting a number of special reports can be prepared to meet the needs of different mangers.

Question 4.
Discuss the advantages of Computerised Accounting Systems over the Manual Accounting Systems.
Answer:
The following are the various advantages of the Computerised Accounting Systems over the Manual Accounting Systems:
a. Speed: The speed of a computer is very high and takes very less time in performing various difficult operations. The accounting data is processed comparatively faster through the Computerised Accounting Systems than it can be done through the manual efforts.

b. Accuracy: In Computerised Accounting Systems, the possibility of errors is minimised or reduced as the primary accounting data is entered only once for preparing various accounting reports and for subsequent usage and processes.

c. Reliability: As the Computerised Accounting Systems is well-equipped in performing repetitive operations, so it is comparatively more reliable to perform the operations than the manual system. Also, the Computerised Accounting Systems overcome the limitation of Manual Accounting Systems such as tiredness, boredom or fatigue, etc., thereby enhances the degree of reliability.

d. Up-to-Date Information: In the Computerised Accounting Systems, whenever the new accounting data is entered and stored, the existing accounting records automatically gets updated.

e. Real-Time User Interface- Most of the automated accounting systems are interlinked through a network of computers. The availability of information to various users at the same time on the real-time basis is facilitated under computerised system of accounting. This is very difficult to avail such facility under manual system as this call for availability of multiple copies of the accounting records that can be accessed by many users at the same time.

f. Automated Document Production: Under Computerised Accounting Systems, the accounting reports such as, Cash Book, Trial balance, Statement of Accounts, etc. is very easy to obtain. This is because most of the computerised systems have standardised and user-defined format of accounting reports that are generated automatically.

g. Scalability: The computerised systems of accounting are highly scalable as there requirement of additional manpower is mainly confined to data entry for recording and storing the additional vouchers in the computers. Thus, the additional cost of processing additional transactions is meagre as compared to the cost associated with hiring new accountants to handle additional transactions.

h. legibility: In Computerised Accounting Systems, the accounting records are typed and presented in standard fonts. The various characters especially numbers, alphabets, graphics, etc. are more clear and can be read without any difficulty and ambiguity.

Question 5.
Describe the various types of accounting software along with their advantages and limitations.
Answer:
The various types of accounting software are:
Ready-to-use Software- This type of software is readily available in the market with prescribed and standard features. This accounting software is basically used by the small size business enterprises, where the number of transactions is not so large. The cost of its installation and maintenance is also low. It has limited number of users, its adaptability is very high as it is relatively easier to learn and operate. It does not have a wide scope to link it with other information systems.

Advantages of Ready-made Accounting Software
a. This software is easily available in the market.
b. It is less expensive, as it comes with basic and standard features.
c. It involves a lesser need for training.
d. It is less sophisticated.
e. Its adaptability is very high as it is relatively easier to learn and operate.
f. It is suitable for small-size business enterprises.

Disadvantages of Ready-made Accounting Software
a. It has limited number of users.
b. It is not suitable for medium and large business organisation, where the number of transactions is very large.
c. It fails to cater the specific needs of the users, d. It suffers from the low level of data secrecy.
e. It does not have a wide scope to link it with other information systems.

Customised Software: Customised software is the software that has standardised features to meet the special requirements of the users. It provides the scope of changing the features of accounting software. The functions of this software can be programmed as per the needs and requirements of the users. This type of software best suits the needs of medium and large businesses. Its cost of installation and maintenance is comparatively higher. It can be easily linked to the other information systems.

Tailored Software: Tailored or Tailor-made accounting software is the software that is developed as per the specifications and requirements of the users. This accounting software is generally used in the large business organisations with multi-user and geographically scattered locations. It is designed to meet the specific needs of the users and form an integral part of the organisational MIS. It has infinite number of users.

Advantages of Customised and Tailor-made Accounting Software
a. This software is suitable for medium and large business organisation.
b. It caters the specific requirements and needs of the users.
c. It can be modified as per the needs of the organisation.
d. It has high level of security’ and minimises the loss and unauthorised access of data.
e. It cannot be easily imitated or duplicated in the market due to difference in the needs and requirements of different users.
f. It does not involve high cost of training as the training can be imparted within the ‘ organisation by the experienced personnel.
g. It can be easily linked to the other information systems, h. It forms an integral part of the organisational MIS.

Disadvantages of Customised and Tailor-made Accounting Software
a. It involves high cost of installation and maintenance.
b. Developing customised software is a time-consuming process and involves high cost of development.
c. Maintenance of this software is difficult as there exists limited availability of knowledge to the developers.
d. It lacks standard training module.

Question 6.
‘Accounting software is an integral part of the Computerised Accounting Systems’ Explain. Briefly list the generic considerations before sourcing accounting software.
Answer:
The accounting software does form an integral part of the Computerised
Accounting Systems. The accounting software should be selected after considering the level of skill and proficiency of the accounting professionals. This is one of the important aspects that should be taken care of before introducing Computerised Accounting Systems, as the accounting professionals are responsible for accounting and the not computers.

The following are some of the important points that should be taken into consideration before introducing accounting software in an organisation.
1. Flexibility: This is the most important factor that should be considered before sourcing accounting software. The accounting software should be flexible in form of data entry, retrieval of data and generating design of reports. The software should be able to run on different computers having different operating systems and having different configurations. It should provide some flexibility among its users.

2. Cost of Installation and Maintenance: The selection of accounting software largely depends upon its cost to the organisation. The cost of accounting software includes cost of installing the related components and hardware, maintenance and alteration costs, cost of training the staff and cost involved in recovering data in case of data failure. An organisation needs to evaluate the benefits of the software against its costs.

3. Size of Organisation The size of an organisation also determines the selection of accounting software. The small-sized organisations, where the volume of business transactions is not so large, usually opt for simple and single user oriented software. On the other hand, large scale organisations, where the volume of business transactions is very large choose the latest and sophisticated software for meeting the multi-user requirements.

4. Training Needs- Another factor that affects the choice of software is the training needs.There is some accounting software that requires comparatively lesser training and is more user-friendly. While, there are some other complicated software that requires continuous and thorough training.

5. Level of Secrecy: The level of expected security is one of the important factors that an organisation bears in mind before sourcing accounting software. Software should be able to prevent the unauthorised access and manipulation of data. It should have in built features of security.

6. Utilities/MIS Reports- Another factor which helps in determining the software selection isthe MIS reports and the extent to which they are used in the organisation.

7. Vendor Reputation and Capability- The selection of software is also affected by the capability and competence of the vendor. It depends upon the reputation of the vendor in the market, the user-reviews of the similar software, the extent of post-sales support services from the vendors, etc.

‘Computerised Accounting Systems are best form of accounting system’. Do you agree? Comment.
Yes, we agree with this statement that ‘Computerised Accounting Systems are best form of accounting system’. It becomes very easier to work with Computerised

Accounting Systems leading to reduction in the accounting errors. Moreover, the computerised accounting reports are highly reliable, thereby enhances the overall efficiency.

Due to the following positive aspects, the Computerised Accounting Systems certainly enjoy an edge over the Manual Accounting Systems.
a. Speed: The speed of a computer is very high and takes very less time in performing various difficult operations. The accounting data is processed Comparatively faster through the Computerised Accounting Systems than it can be done through the manual efforts.

b. Accuracy: In Computerised Accounting Systems, the possibility of errors is minimised or reduced as the primary accounting data is entered only once for preparing various accounting reports and for subsequent usage and processes.

c. Reliability: As the Computerised Accounting Systems is well-equipped in performing repetitive operations, so it is comparatively more reliable to perform the operations than the manual system. Also, the Computerised Accounting Systems overcome the limitation of Manual Accounting Systems such as tiredness, boredom or fatigue, etc., thereby enhances the degree of reliability.

d. Up-to-Date Information: In the Computerised Accounting Systems, whenever the new accounting data is entered and stored, the existing accounting records automatically gets updated.

e. Real-Time User Interface- Most of the automated accounting systems are interlinked through a network of computers. The availability of information to various users at the same time on the real-time basis is facilitated under computerised system of accounting.

f. Automated Document Production: Under Computerised Accounting Systems, the accounting reports such as, Cash Book, Trial balance, Statement of Accounts, etc. is very easy to obtain. This is because most of the computerised systems have standardised and user-defined format of accounting reports that are generated automatically.

g. Scalability: The computerised systems of accounting are highly scalable as the requirement of additional manpower is mainly confined to data entry for recording and storing the additional vouchers in the computers. Thus, the additional cost of processing additional transactions is meagre as compared to the cost associated with hiring new accountants to handle additional transactions.

h. Legibility: In Computerised Accounting Systems, the accounting records are typed and presented in standard fonts. The various characters especially numbers, alphabets, graphics, etc. are more clear and can be read without any difficulty and ambiguity.

You can Download Chapter 6 Shishu Makkaligolida Madeva Questions and Answers Pdf, Notes, Summary, 1st PUC Kannada Textbook Answers, Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.

Karnataka 1st PUC Kannada Textbook Answers Sahitya Sanchalana Chapter 6 Shishu Makkaligolida Madeva

Shishu Makkaligolida Madeva Questions and Answers, Notes, Summary

You can Download Chapter 8 Redox Reactions Questions and Answers, Notes, 1st PUC Chemistry Question Bank with Answers Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.

Karnataka 1st PUC Chemistry Question Bank Chapter 8 Redox Reactions

1st PUC Chemistry Redox Reactions One Mark Questions and Answers

Question 1.
Define oxidation in terms of electronic concept.
Answer:
Oxidation is a process in which loss of electrons take place.

Question 2.
Define by reduction in terms of electronic concept.
Answer:
Reduction is a process in which gain of electrons takes place.

Question 3.
What are redox reactions ? Give an example.
Answer:
Redox reaction is reaction in which oxidation and reduction take place
simultaneously, e.g. Zn(s)+ Cu²⁺ (aq) → Zn²⁺ (aq) + Cu(s):

Question 4.
What is oxidation number of alkali metals in their compounds?
Answer:
+1.

Question 5.
Zn(s)+Cu²⁺ → Zn²⁺ + Cu(s) is this reaction redox reaction ? If yes, name the
∴ oxidizing agent as well as reducing agent.
Answer:
Yes, Cu²⁺ is oxidising agent whereas Zn is reducing agent.

Question 6.
Which of the following does not conduct electric current and why?
Molten NaCl, Solid Pb, AgNO₃ solution and methanol.
Answer:
Methanol will not conduct electric current because it does not ionise. .

Question 7.
Define cathode and anode.
Answer:
Cathode is electrode towards which cations are attracted. Anode is electrode which : attracts anions.

Question 8.
What is oxidation state of Cr in CrO⁵ and why?
Answer:
Cr has +6 oxidation state because it has 6 valence electrons, therefore can form 6 covalent bonds.

Question 9.

which is the strongest oxidising agent out of them ?
Answer:
Fe³⁺ is strongest oxidising agent because it has standard reducing potential. (i.e., +ve value) value.

Question 10.
What is meant by oxidation potential of an electrode ?
Answer:
Oxidation potential measures the tendency of an element or anion to lose the electrons.

Question 11.
What is relationship between standard oxidation potential and standard reduction potential?
Answer:
Both are equal in magnitude but opposite in sign.

Question 12.
Identify the oxidant and reductant in the following reactions :
(i) Zn(s) + \(\frac { 1 }{ 2 }\) O₂(g) → ZnO(s)
(ii) Zn(s) + 2H⁺ (aq) → Zn²⁺(aq) + H₂(g)
Answer:
(i) Zn is reducing agent (reductant) and O₂ is oxidizing agent (oxidant)
(ii) Zn is reducing agent (reductant) whereas H⁺ is oxidizing agent (oxidant).

Question 13.
How will you define (i) Oxidant and (ii) Reductant in terms of oxidation no.?
Answer:
(i) Oxidant: Which decreases its own oxidation no. and increases the ox. no. of the other in a reaction.
(ii) Reductant : Which increases its own ox. no. and decreases that of other in a chemical reaction.

Question 14.
What do you mean by disproportionation reaction ?
Answer:
A disproportionation reaction is an oxidation-reduction process in which the same substance is oxidized and reduced e.g., 2Cu⁺ → Cu + Cu²⁺

Question 15.
Determine the oxidation number of C in the following : C₂H₆, C₄H₁₀, CO, CO₂ and HCO₃^–
Answer:
O.N. of C = -3 in C₂H₆ ; -2.5 in C₄H₁₀ ; +2 in CO ; +4 in CO₂ and +4 in HCO₃^–

Question 16.
Determine the oxidation number of O in the followiing : Na₂O₂ and CH₃COOH.
Answer:
O.N. of+1 in Na₂O₂ and -2 in CH₃COOH

Question 17.
Find out the oxidation number of sulphur in the following species : and HSO₄^–.
Answer:
O.N. of S = + 6 in HSO₄^–.

Question 18.
Determine the oxidation number of all the atoms in the following well known oxidants KCI04.
Answer:
K = +1, Cl = +7, O = -2

Question 19.
Determine the change in the oxidation number of S in H₂S and SO₂ in the following industrial reaction : 2H₂S(g) + SO₂(g) → 3S(g) + 2H₂O(g)
Answer:
O.N. of S changes from -2 in H₂S and +4 in SO₂ to zero in elemental sulphur.

Question 20.
What is oxidised and what is reduced in the reaction ?
H₂S + Cl₂ → 2HCl + S
Answer:
H₂S is oxidised to S and Cl₂ is reduced to HCl.

Question 21.
In the reaction SnCl₂ + 2HgCl₂ → SnCl₄ + Hg₂Cl₂
which is oxidant and which is reductant ?
Answer:
SnCl₂ is a reductant and HgCl₂ is an oxidant.

Question 22.
Identify the strongest and weakest reducing agents from the following list: Zn, Cu, Ag, Na, Sn.
Answer:
Strongest reducing agent in Zn and weakest reducing agent in Ag.

Question 23.
Can oxidation number of an atom in a chemical species he fractional ? Illustrate by an example.
Answer:
Yes, it can be fractional. For example oxidation no. of Pb in Pb₃O₄ = + \(\frac { 8 }{ 3 }\)

1st PUC Chemistry Redox Reactions Two Marks Questions and Answers

Question 1.
Calculate the oxidation number of underlined atoms in the following compounds and ions: CH₄, Sb₂O₅, C₆H₁₂O₆
Answer:
CH₄
X + 4 = 0;
X = -4

Sb₂O₅
2x – 10= 0;
2x = 10
x = +5

C₆H₁₂O₆
6x + 12 – 12 = 0
x = 0

Question 2.
Identify the oxidant and reductant in the following chemical reaction:
2I^– (aq) + Cl₂ (g) → 2Cl^– (aq) + I₂(s)
Answer:
2I^– (aq) + Cl₂ (g) → 2Cl^– (aq) + I₂(s)
Oxidant is Cl₂ (g) reductant is I^– (aq)

Question 3.
The standard reduction potentials of Al and Ni are -1.66 V and -0.28 V, respectively. Is Al a stronger or weaker reducing agent than Ni ? Explain.
Answer:
‘Al’ is stronger reducing agent than Ni because it has lower reduction potential. Al³⁺ is more stable than Ni²⁺ ion.

Question 4.
The standard reduction potentials of Zn²⁺, Mg²⁺ and Na⁺ are -0.76 V, -2.37 V and -2.71 Y respectively, which of the following is the strongest oxidizing agent?
Answer:
Zn²⁺ is strongest oxidising agent. It can gain electrons easily. It has highest standard reduction potential.

Question 5.
Which of the following is best reducing agent and why ? Li, Cu, Br₂, F₂, H₂, K.
Answer:
Lithium (Li) is best reducing agent because it has lowest standard reduction potential, i.e., Li⁺ is most stable.

Question 6.
Calculate the oxidation number of (i) C in CH₂Cl₂ and (iii) Pb in Pb₃O₄.
Answer:
(i) C in CH₂Cl₂. Let the oxidation number of C in CH₂Cl₂ be x. Writing the oxidation number of each atom above its symbol.

x + 2(+1) + 2(-1) = 0 ,x = 0

Question 7.
Balance the equation by ion electron method.
Fe(OH)₂(s) + H₂O₂ → Fe(OH)₃ (s) + H₂O is basic solution.
Answer:

Question 8.
Balance the equation by ion electron method.
Al(s) + NO₃ → Al(OH)₄^– + NH₃ in basic solution.
Answer:

Question 9.
Balance the equation by ion electron method.
PbO₂ + Cl^– → ClO^–+ [Pb(OH)₃]^– in basic solution.
Answer:
Here 2e^– + PbO₂ → [Pb(OH)₃]^–
2H₂O + 2e^–PbO2₂ → [Pb(OH)₃] + OH^– …(I)
2OH + Cl^– → ClO^– + 2e^–+H₂O …(ii) Add(i)&(ii)
PbO₂ + OH^– + Cl^– + H₂O → [Pb(OH)₃ ]^– + ClO^–

Question 10.
Balance the equation by ion electron method.
CrO₄^– + H₂O₂ →CrO₄^2- in basic solution.
Answer:
[2OH^– + CrO^–₃ → CrO₄^2- + e^– + H₂O] x 2 …(i)
2e^–+ H₂O₂ → 2OH^– …(ii) (Add(i) & (ii))
2OH^–+2CrO₃^– +H₂O₂ → 2CrO₄^2-+ 2H₂O

Question 11.
Starting with the correctly balanced half reactions write the overall net ionic reactions. Chloride ion is form oxidized to Cl₂ by MnO₄^– in acid
Answer:

Question 12.
Starting with the correctly balanced half reactions write the overall net ionic reactions for HNO₂ reduces MnO₄^– in acid solution.
Answer:

Question 13.
Starting with the correctly balanced half reactions write the overall net ionic reactions for HNO₂ oxidizes I^– to I₂ in acid solution.
Answer:

Question 14.
Starting with the correctly balanced half reactions write the overall net ionic reactions. ClO₃^– oxidizes Mn²⁺ to MnO₂(s) in acid solution.
Answer:

Question 15.
Consider the following cell notation :
Al(s)|Al³⁺(aq)|Ni²⁺(aq)|Ni(s), here
Which substances act as anode ? Which of them acts as cathode ? Write the net ionic equation for the cell reaction.
Answer:
At acts as anode, Ni acts as cathode.

Question 16.
Describe the standard half cell that is used in electrochemistry to measure standard potentials. Write an equation for its half reaction and show its standard potential.
Answer:
Standard hydrogen elctrode is used to measure standard electrode potential.
It consists of H₂(g) filled at 1 atm, 298 K in a sealed tube having Pt rod for metallic contact, coated with platinum black which acts as catalyst. It is dipped in 1 M solution of HCl. The reaction 2H⁺ (aq) + 2e^– → H₂(g) \(\mathrm{E}_{\mathrm{H}^{+} / \mathrm{H}_{2}}^{\circ}=0\)

Question 17.
Calculate the E°_cell using these electrodes whose half reactions are:
Fe(OH)₂(s) + 2e^– → Fe(s) + 2OH^–(aq)  E° = -0.88V
NiO₂(s) + 2H₂O(l) + 2e^– → Ni(OH)₂(s) + 2OH^–(aq)  E° = +0.49V
Answer:

Question 18.
Calculate E°_cell for the reaction Cl₂(g) + 2l^– → I₂(s) + 2Cl^–(aq) with the help of these half cell reactions:
Cl₂ (g) + 2e^– → 2Cl^–(aq) ; E° = +1.36V
I₂(g) + 2e^– → 2I^–(aq) ;E° = +0.54V
Answer:

Question 19.
(a) Give one use of heavy water in nuclear reactor.
(b) Write down balanced chemical equations of the reaction of cone. Nitric acid with (i) Copper and (ii) Iodine.
Answer:
(a) Heavy water is used as moderate and coolant in nuclear reactor.
(b) (i) Cu(s) + 4HNO₃(conc.) → Cu(NO₃)₂ + 2NO₂ + 2H₂O

Question 20.
Balance the following ionic reaction with the help of oxidation number method : MnO₄^– + I^– → MnO₂ + IO₃^– (alkaline medium)
Answer:
MnO₄^– + I^– → MnO₂ + IO₃^– (alkaline medium)
H₂O + 2MnO₄^– + I^– → 2MnO₂ + IO₃^– + 2OH^– is balanced equation.

Question 21.
Complete the following equations :
(a) PbS(s) + H₂O₂(aq) → ………………………… (b) MnO₄^–(aq) + H₂O₂ →………………….
Answer:
PbS + 4H₂O₂ → PbSO₄ +4H₂O
2MnO₄^– + 3H₂O₂ → 2MnO₂ + 3O₂ + 2H₂O + 2OH^–

Question 22.
Write the cell reactions for Zn|Zn²⁺(lM)||cd²⁺(lM)|Cd
E°Zn²⁺ /Zn = -0.76V, E°Cd²⁺ /Cd = 0.40V
Answer:

Question 23.
Zinc Silver oxide cell is used in heating aids or utensils and electric watches:
Zn → Zn²⁺ + 2e^–; E° = +0.76V
Ag₂O + H₂O + 2e^– → 2Ag + 2OH^–; E° = +0.80V
Which is oxidized and reduced?
Answer:
Zn is oxidised, Ag₂O is reduced.

Question 24.
The standard emf value of some elements are listed below at 298 K. Which of the following two electrodes should be combined to form a cell having highest emf ? Identify the cathode and anode and write the cell reaction. Also mention the direction of flow of electrons in the external and internal circuit.

Answer:
For maximum emf; anode should have minimum reduction potential and cathode should have maximum reduction potential. Hence A²⁺ / A couple should be anode and C²⁺/C couple acts as cathode.
Cell reaction A + C²⁺ → A²⁺ + C
Direction of flow of electrons is from A to C in external and from C to A internal circuit. Direction of flow of current is opposite to the direction of flow of electrons.

Question 25.
Silver jewellery turns greyish black due to the formation of Ag₂S layer on it. Can this tarnish be removed by dipping tarnished jewllery in an aluminium vessel containing inert electrolytic solution. The standard electrode potential for the half reactions are given below :
Ag₂S + 2e^– → 2Ag + S^2-; E° =-0.71V ;and Al³⁺ +3e^– →Al; E° = -1.66V
Answer:
Tarnish (black colour) will be removed if the following reaction occur.
Al + Ag₂S → A1³⁺ +2Ag + S² ; here E° for this reaction = -0.71-(-1.66) = 0.95 V
EMF is positive. ∆G will be negative this reaction will occur and tarnish will be removed.

Question 26.
Justify that the reaction : 2Na(s) + H₂(g) → 2NaH is a redox reaction.
Answer:
In this reaction, Na is oxidised to Na⁺ and hydrogen is reduced from H2 and H- ion. Therefore it is a redox reaction.
2Na⁰ + H2⁰ → 2Na⁺ H^-1 (s)

Question 27.
Out of silver and aluminium vessel which one will be more suitable to store 1 M HCl solution and why ?
Answer:
Since reduction potential of silver is more than that of hydrogen (E°H⁺ /H₂Pt = 0), silver vessel will be suitable to store 1 M HCl. On the other hand E° of Al³⁺ /Al is less than that of hydrogen (E°H⁺ /H₂Pt) so that hydrogen will be liberated is stored in aluminium vessel.

Question 28.
What is the oxidation number of Cr in (i) K₂CrO₄ (ii) Ni and Ni(CO)₄
Answer:
Let the Ox. no. of Cr in K₂CrO₄ be x.
2(+1) + x + 4(-2) = 0
+2 + X – 8 = 0
x = +6
Ox. no. of Cr in K₂CrO₄ = +6 A
Ox. state of Ni in Ni(CO)₄ is x + 4(0) = 0;x – 0
Ox. state of Fe in Fe(CO)₅ is x + 5(0) = 0 or x = 0

Question 29.
Can Fe³⁺ oxidize Br^– to Br₂ at 1 m concentrations ?
Answer:
E°(Fe³⁺/ Fe²⁺) is lower than that of E°(Br / B^–). Therefore Fe²⁺ reduce Br₂ but Br^– cannot reduce Fe³⁺ . Thus Fe³⁺ cannot oxidize Br^– to Br₂.

Question 30.
What is the oxidation state of S in (i) H₂SO₃ (ii) P₄ (ii) (iii) PH₃ (iv) H₃PO₄
Answer:
(i) H₂SO₃ :2(+1) + x + 3(-2) = 0
x = +4
Ox. state of is IV in H₂SO₃
Answer:
(i) Ox. no. of P in P₄ = 0
(iii) Ox. no. of P in H₃PO₄ .
3(+1) + x + 4(-2) = 0
+3 + x – 8 = 0
x = +5
Ox. no. of P in H₃PO₄ = +5

Question 31.
An iron rod is immersed in a solution containing NiSO₄ and ZnSO₄. When the concentration of each salt is 1M, predict giving reasons which of the following reactions is likely to proceed ? (i) Iron reduces Zn²⁺ ions, (ii) Iron reduces Ni²⁺ ions.
Answer:
Given : E°(Zn²⁺ /Zn) = 0.76V, E°(Fe²⁺ /Fe) = 0.44V and E°(Ni²⁺ /Ni) = 0.25V
Answer:
(i) The reduction potential of iron is more than that of zinc. Therefore, iron will be reduced. In other words Zn²⁺ will not be reduced.
(ii) The reduction potential of Ni²⁺ is more than that of Iron. Therefore, Ni²⁺ will be reduced by iron.

Question 32.
Which of the following redox reaction is oxidation and which is reduction?
(i) Zn → Zn²⁺ + 2e^–
(ii) Cl2 + 2e^– → 2Cl^–
(iii) Fe → Fe²⁺ + 2e^–
(iv) Sn⁴⁺ + 2e^– → Sn²⁺
Answer:
(i) Oxidation
(ii) Reduction
(iii) Oxidation
(iv) Reduction

Question 33.
Arrange the molecules, NH₃, NO₃, HN₃, NO₂^–, N₂O₄ and N₂H₄ in the decreasing order of the oxidation states of nitrogen.
Answer:

Question 34.
Determine the change in oxidation number of S in H₂S and SO₂ in the following industrial process: 2H₂S + SO₂ → 3S + 2H₂O
Answer:
Let us write the oxidation numbers of atoms of all the reactants and products taking part in the reaction:

O.N. of S in H₂S increases by 2 O.N. of S in SO₂ decreases by 4

Question 35.
Can the reaction Cr₃O₇^2- + H₂O ⇌ CrO₄^2- +2H⁺ be regarded as a redox reaction ?
Answer:
Ox. no. of Cr in Cr₂O₇^2- ⇌ +6 Ox. no. of Cr in Cr₂O₇^2-= +6
Since the ox. no. of Cr has neither increased nor decreased in the above reaction, therefore this reaction cannot be regarded as a redox reaction.

Question 36.
Balance the oxidation reduction reaction FeS₂ + O₂ → Fe₂O₃ + SO₂
Answer:

Question 37.
Which of the two ClO₂^– or ClO₄^– show disproportionation reaction and why ?
Answer:
The oxidation state of Cl in ClO₂ is +3 and in ClO₄ is +7. Chlorine is present in highest oxidation state of +7 in ClO₄^– and it cannot increase its oxidation state. Hence ClO₄^– is not disproportionate.
The disproportion reaction of ClO₂^– is

Question 38.
Which type of electrolytic are used in salt bridge ?
Answer:
Only those electrolytes for which cations and anions have nearly the same ionic mobilities (i.e. distance travelled by an ion per second under a potential gradient of one voltmeter) are used as electrolytes in the salt bridge. Thus KCl, KNO₃, K₄SO₄, and NH₄NO₃ are preferred over NaCl, NaNO₃ and Na₂SO₄.

Question 39.
Mention the cation and anion which have highest ionic mobility.
Answer:
Among cations, H⁺ ion has the highest ionic mobility and among anions, OH^– has the highest ionic mobility.

Question 40.
The standard electrode potential corresponding to the reaction Au³⁺(aq) + 3e^– → Au(s) is 1.5 V. Predict if gold can be dissolved in 1M HCl solution and on passing hydrogen gas through gold salt solution, metallic gold will be precipitated or not.
Answer:
Consider the half reaction, 2H⁺(aq) + 2e^– → H₂(g); E° = 0.0V
Au³⁺(aq) + 3e^– → Au(s); E° = 1.50V
Since E° (1.50V) for (Au³⁺ / Au) is higher than that H+ / – \(\frac { 1 }{ 2 }\)H₂ (0.0V), therefore, Au³⁺
can be more easily reduced than H⁺ ions Au³⁺ can be reduced to Au metal by H₂ butr H⁺ cannot oxidize metallic gold to Au³⁺ ions. In other words, metallic gold does not dissolve in 1M HCl instead H₂ gas can reduce gold salt to metallic gold.

Question 41.
What is the oxidation number of S in (i) Na₂S₄O₆, (ii) S₂Cl₂?
Answer:
(i)

In b & c, s has oxidation number is zero. In a & d s has oxidation number +5
(ii)

Question 42.
What is the name of the reaction ?
2CH₃CH₂CH₂SH → cCH₃CH₂CH₂ – S – S – CH₂CH₂CH₃
Whether condensation, oxidation, reduction or polymerization?
Answer:
This is an example of oxidation reaction since two H-atoms have been removed.

Question 43.
Both Cr₂O₇^2-(aq) and MnO₄^– (aq) can be used to titrate Fe²⁺(aq). If a given titration, 24.50 cm3 of 0.1 M Cr₂O₇^2- were used, then what volume of 0.1 M MnO₄^– solution would have been used for the same titration ?
Answer:
Suppose V₂cm³ of M₂Fe²⁺ is titrated against 24.50 cm3 0.1M Cr₂O₇^2-  and V₁cm³ of 0.1M MnO₄^– solution, then

1st PUC Chemistry Redox Reactions Three/Four Marks Questions and Answers

Question 1.
Balance MnO₂ + HCl → MnCl₂ + Cl₂ + H₂O
Answer:
Solution x
Step – 1: Assign oxidation number:

Step – 2 : Write the oxidation number changes.
Change in oxidation number of Mn + 4 to +2 = 2
Change in oxidation number of Cl – 1 to 0 = +1

Step – 3 : Cross multiply the numbers. Co-efficient 2 is multiplied to HCl and 1 is multiplied to MnO₂.
MnO₂ + 2HCl → MnCl₂+H₂O + Cl₂

Step – 4 : Check the oxidation number, and 2 molecules of HC1 on left hand side to balance the chlorine atoms of MnCl₂. In order to balance oxygen and hydrogen atom 2 molecule of H₂O has to be added on the right hand side.
MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂

Question 2.
Balance Fe²⁺+ Cr₂O₇^2- → Fe³⁺ + Cr³⁺ is acid media.
Answer:
Solution:
Step -1: (LEO = Loss of Electron Oxidation)

(GER = Gain of Electron Reduction)

Step-2: Fe²⁺ → Fe³⁺ … (1) (2 → 3 = 1 unit ON) ,
Cr₂O₇^2- → 2Cr³⁺ … (2) (+6 →+3 = 3 units 2 sets => 6 units ON)

Step – 3 : Cross multiplication i.e., (1) x 6 and (2) x 1
(1) x 6 ⇒ 6Fe²⁺ → 6Fe³⁺ … (3)
(2) x 1 ⇒ Cr₂O₇^-2 → 2Cr³⁺ …(4)

Step – 4 : Add (3) + (4) ⇒ 6Fe²⁺ + Cr₂O₇^2- → 6Fe³⁺ + 2Cr³⁺

Step – 5 : Balance Oxygen and then Hydrogen
6Fe²⁺ + Cr₂O₇^2- + 14H⁺ → 6Fe³⁺ + 2Cr³⁺+ 7H₂O

Question 3.
Evaluate the equivalent weight of I2 from the following equation.
I₂ + 2S₂O₃ → S₄O₆^2-+2I^–
Answer:

Question 4.
Find equivalent weight of KMnO₄ from

Answer:
Balance the given equation
2KMnO₄ + 3H₂SO₄ → K₂SO₄ + 2MnSO₄ + 3H₂O + 5[O]

Method – 1: Stoichiometry
We know equivalent weight of Oxygen = 8
Atomic weight of Oxygen = 16
∴ 2 equivalent of oxygen = 1 Atomic weight of oxygen
Here 5[O] = 10 equivalent of oxygen

Method – 2 : (Oxidation Number)
2 KMnO₄ + 3H₂SO₄ → K₂SO₄ + 2MnSO₄ + 3H₂O + 5[O]
+7 ← 5 Unit GER Reduction → +3
KMnO₄ acts as oxidising agent

Question 5.
Evaluate the equivalent weight of oxidizing and reducing agents in the
following reaction (4M) K₂Cr₂0₇ +FeS0₄ >Cr³⁺ +Fe³⁺
Answer:
Assigning oxidation number,

Question 6.
The half cell reaction with their oxidation potentials are
Pb(s) → Pb²⁺(aq) + 2e^–; E^o_cell = +0.13V
Ag(s) → Ag(aq) + e^–; E^o_cell = -0.80V
Write the cell reaction and calculate its EMF.
Answer:
Rewrite the two equations in the reduction form thus.
Pb²⁺ (aq) + 2eE^– → Pb(s) ; E° = -0.13V .. (i)
Ag⁺(aq) + e^– → Ag(s) ; E° = +0.80V …(ii)
To obtain the equation for the cell reaction, multiply Eq. (ii) with 2 and subtract Eq. (i) from it, we have,
Pb(s) + 2Ag⁺(aq) → Pb²⁺(aq) + 2Ag(s) ; E^o_cell =+0.80-(-0.13) =+0.93V

Question 7.
Justify that the reaction ; 2Cu₂O(s) + Cu₂S(s) → 6Cu(s) + SO₂(g) is a redox
reaction. Identify the species oxidized, reduced, which acts as oxidation and which acts as reductant.
Answer:
Writing the oxidation number of each atom above its symbol we have,

Here, in the reaction, the oxidation number of copper decreases from +1 in Cu₂O or Cu₂S to 0 in copper metal, therefore, copper is reduced and is .oxidizing agent or oxidants. Further, the oxidation number of S increases from -2 in Cu₂S to +4 in SO₂. Therefore, sulphur is oxidized. Thus, it is reducing agent of reductant.

Question 8.
Using stock notation, represent the following compounds : HAuCl₂ , TI₂O, FeO, Fe₂O₃, Cul, CuO, MnO and MnO₂.
Answer:
By applying the various rules for determining the oxidation number of different atoms in a compound, the oxidation number of each metallic element in the given compounds is as follows:
In HAuCl₂ , Au has +3; in TI₂0, TI has +1; in FeO, Fe has +2; in Fe₂O₂ , Fe has +3 ; . in Cul, Cu has +1 : in CuO, Cu has +2 ; in MnO, Mn has +2 while in Mn₂O , Mn has +4 oxidation state. Therefore, these compounds may be represent as :
HAu(II)Cl₄, Tl₂(1)O, Fe(II)O, Fe₂(III)O₃, Cu(I)I, Cu(II)O, Mn(II)O, and Mn(IV)O₂.

Question 9.
Balance the equation, Mg(aq) + HNO₃(aq) → Mg(NO₃)₂(aq) + N₂O(g) + H₂O(1)
Answer:
Find out the elements which undergo a change in oxidation number (O.N.)
O.N. increases by 2 per Mg atom

Here, O.N. of Mg increases from 0 in Mg metal to +2 in Mg(NO₃)₂ and that of N decreases from +5 in HNO₃ to +1 in N₂O.

Question 10.
Split the following redox reactions into the oxidation and reduction half reactions.
(a) 2K(s) + Cl₂(g) →2KCl(s) (b) 2Al(s) + 3Cu²⁺(aq) → 2Al³⁺+(aq) + 3Cu(s)
Answer:

Question 11.
Predict the oxidation state of (a) C in C₃O₂, (b) Cr in Br₃O₃, (c) S in S₃O₃^2-
Answer:
(a) The structure of C₃O₂ (carbon -2 +2 0 +2 -2 suboxide) isO = C = C = C = 0 each of the two terminal oxygen atoms have an oxidation state of -2 and the carbons to which they are atteached have an oxidation state of +2. (Since when ever a covalent bond is formed between similar atoms, each of the atoms is given an oxidation state of zero), therefore, the oxidation state of central carbon atom in C₃O₂ is zero.

Thus, the two terminal carbon atoms are present in +2 oxidation state each, whereas the third one is present in zero oxidation state. Therefore, the average oxidation state of carbon in

(b) Tribromooctaoxide (Br₃O₈)

We can easily find out that the terminal bromine atoms are present in +6 oxidation state while the middle one has an oxidation state of +4. However, the average oxidation number of Br in Br308 turns out to be

(c) Tetrathionate ion

Since each of the two terminal sulphur atoms is connected to two oxygen atoms by a double bond and one oxygen atom by a single bond, therefore, the oxidation state of each of these terminal sulphur atoms is +5.

Since two central sulphur atoms are linked to each other by a single bond and each sulphur is further attached to similar species on either side, the electron pair forming the S – S bond remain in the centre and hence each of the two central sulphur atoms has an oxidation state of zero.
However, the average oxidation state of the sulphur atoms is

Question 12.
Mention which is reduced and oxidized in the following reaction :
(a) 4Na(s) + O₂(g) → 2Na₂0(s)
(b) 2Na(s) + Cl₂(g) → 2NaCl(s) ,
(c) 2Na(s) + S(s) → Na₂S(s)
Answer:

Question 13.
Identify the oxidant and reductant in the following reactions :
(a) 10H⁺ (aq) + 4Zn(s) + NO₃^– (aq) → 4Zn²⁺(aq) + NH⁺₄ +3H₂O(l)
(b) I₂(g) + H₂S(g) → 2IH(g) + S(s)
Ans:
(a) Writing the O.N. of all the atoms above their symbols, we have

O.N. of Zn changes from zero in Zn to +2 in Zn²⁺ and, therefore, it is oxidized and hence Zn acts as a reductant.
The O.N. of N decreases from +5 in NO₃^– to -3 in NO₄⁺ and, therefore, it is reduced and hence NO₃^– _{acts as the oxidant.}

(b) Writing the ON of all the atoms above their symbols, we have

The ON of I₂ decreases from zero in I2 to -1 in HI, therefore, I₂ is reduced and hence it acts as on oxidant.
The O.N. of S increases from -2 in H₂S to zero in S, therefore, H₂S is oxidized and hence it acts as the reductant.

Question 14.
0.2g of a sample of H₂O₂ reduced 20 ml of 0.1M KMnO₄ solution in acidic medium. What is the percentage purity of H₂O₂ ?
Answer:
No of moles of KMnO₄ present in 20ml of 0.1M
KMnCh solution = \(\frac{20}{1000}\) x 0.1 = 2 x 10^-3

The balanced equation for the redox reactions is :
2KMnO₄ + 5H₂O₂ + 3H₂SO₄ → K₂SO₄ + 2MnSO₄ + 8H₂O + 5O₂ …(1)
From the equation, 2 moles of KMnO₄ = 5 moles of H₂O₂.
2 x 10^-3 moles of KMnO₄ will react with H₂O₂ = \(\frac{5}{2}\) x 2 x 10^-3 = 5 x 10^-3 moles
Molecular wt. of H₂O₂ = 34
Amount of H2O2 actually present = 34 x 5 x 10^-3 = 0.17g .
Percentage purity of in 20 ml is =  \(\frac{0.17}{0.20}\) x l00 = 85

Question 15.
16.6g of pure potassium iodide was dissolved in water and the solution was . made upto one litre. V cm³ of this solution was acidified with 20 cm³ of 2M HCl. The resulting solution required 10 cm3 of decinormal KlO₃ for complete oxidation of I- ions to ICl. Find out the value of V.
Answer:
The chemical equation for the redox reactions is :

Question 16.
Which of the following species, do not show disproportionation reaction and why ? CIO^–, CIO₂^–, CIO₃^– and CIO₄^– Also write reactions for each of the species that disproportionates.
Answer:
The oxidation state of Cl in all the given species are :

Out of above species, CIO₄^– does not undergo disproportionation since in this oxoanion chlorine is already present in the highest oxidation state of +7 and hence cannot be further oxidized.

All the remaining oxoanions have oxidation state lower than the highest (i.e., +7) and higher than the lowest (i.e. -1) therefore, all these species undergo disproportionation reactions as shown below.

Question 17.
How does CU₂O act as both oxidant and reductant ? Explain with proper reactions showing the change of oxidation numbers in each example.
Answer:
Cu₂O undergoes disproportionation to form Cu²⁺ and Cu.
2Cu²⁺(aq) >Cu²⁺(aq) + Cu(s)
Thus, Cu₂O acts both as an oxidant as well as a reductant.
(i)

and Cu₂O acts as a reductant and reduces O₂ to O^2-

(ii) When heated with Cu₂S it oxidizes S^2- to SO₂ and hence Cu₂O acts as an oxidants

Question 18.
Determine the volume of \(\frac { M }{ 8 }\) KMnO₄ solution required to react completely with 25.0cm3 \(\frac { M }{ 4 }M/4\) FeSO₄ solution in acidic medium.
Answer:
The balanced ionic equation for the reaction is
MnO₄^–+ 5Fe²⁺ + 8H⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O
From the balanced equation, it is evident that 1 mole of KMnO₄ = 5 moles of FeSO₄.
Applying molarity equation to the balanced redox equation,

Thus, the volume of \(\frac { M }{ 4 }M/4\) KMnO₄ solution required =10.0 ml.

Question 19.
Calculate the concentration of hypo (Na₂S₂O₃.5H₂O) solution in gdm^-3 if 10.0ml of this solution decolourised 15mL of M/40 iodine solution.
Answer:
The balanced equation for the redox reaction is 2S₂O₃^2- + I₂ → 2I^– + S₄O₆ ^2-
From the balanced equation, it is evident that 2 moles of Na₂S₂C>O₃ ≡ 1 mole of I₂.

Question 20.
Calculate the volume of 0.05M KMnO₄ solution required to oxidize completely 2.70g of oxalic acid (H₂C₂O₄) in acidic medium.
Answer:
Balanced equation for the redox reaction is :
2KMnO₄ + 5(COOH)₂ + 3H₂SO₄ → K₂SO₄ + 2MnSO₄ + 10CO₂ + 8H₂O
No of moles oxalic acid = 2.70/90 = 0.03 mole
From the balanced equation, 5 moles of (COOH)₂ = 2 mole KMn0₄ .
Then 0.03 mole (COOH)₂ = pppp— x 0.03 = 0.012 moles of KM_nO₄.
Now, 0.05 mole of KMnO₄ is present in solution given = 1000 cm³.
0.012 mole of KMnO₄ is present in solution = \(\frac { 2 }{ 5 }\) = 240 cm³

Question 21.
Write the rules for assigning oxidation number.
Answer:

• All atoms in the elemental or molecular state have ‘zero’ oxidation state.
• Elements of group I and II in the periodic table always have ‘+1’ and ‘+2’ oxidation sstates respectively.
• Hydrogen ‘+1’ oxidation state in all its compounds except metal hydrides where it is ‘-1’
• Oxygen has been assigned an oxidation number of ‘-2’ in all its compounds except peroxides and oxygen fluoride. In peroxide it is ‘-1’ and in oxygen fluoride it is ‘+2’.
• Halogens generally have ‘-1’ oxidation state. Except fluorine, other halogens may have positive oxidation states in their oxides and inter halogen compounds (Fluorine always has ‘-1’ state).
• The algebraic sum of oxidation numbers of all the elements in a compound is zero and that in an ion is equal to the net charge on the ion.

Question 22.
Balance MnO₄^– + Fe²⁺ → Fe³⁺ + Mn²⁺ in acidic medium by ion electron method.
Answer:
MnO₄^– + Fe²⁺ → Fe³⁺ +Mn²⁺
[Fe²⁺ → Fe³⁺] x 5 ……………(i)
8H⁺ + MnO₄^– >Mn²⁺ + 4H₂O …(ii)
… (ii) Adding (i) and (ii), we get
5Fe²⁺ + 8H⁺ + MnO₄^– → Mn²⁺ + 4H₂O + 5Fe³⁺

Question 23.
Find the oxidation state of sulphur in the following compounds :
Answer:

Question 24.
Find the oxidation number of element underlined in the following species :

Answer:

Question 25.
Calculate the oxidation number of (i) N in NO₃^– ; (ii) P in H₃P₂O₇^– CO₃^2-.
Answer:
(i) N in NO₃^– , let the oxidation number of N in NO₃^– be x. Writing the oxidation number of each atom above its symbol. \(\begin{array}{cc}{\mathbf{x}} & {-2} \\ {\mathbf{N}} & {\mathbf{O}_{3}}\end{array}\)
x + 3(-2) = -1
x – 6 = -1, x = +5
(ii) P in H₃P₂O₇^– , let the oxidation number of P in H₃P₂O₇^– be x. Writing the oxidation
number of each atom above its symbol.
\(\begin{array}{ll}{\text { th } x} & {-2} \\ {\text { H }_{3} P_{2}} & {\text { o_{ } }}\end{array}\)
H₃P₂O₇^–= 3(+1) + 2 (x) = -1 +7(-2) or 2x – 11 = -1; x = + 5
Thus, the oxidation number of P in H₃P₂O₇^– is +5.

Question 26.
What is the oxidation number of metals (i) [Fe(CN)₆ ]^4- and (ii) MnO₄^– ?
Answer:
(i) Fe in [Fe(CN)₆ ]^4-. Let the oxidation number of Fe in [Fe(CN)₆ ]^4- bexand CN be -1 i.e..,

∴  Sum of oxidation numbers of all the atoms in
[Fe(CN)₆ ]^4- =x + 6(-l) = -4 = x-6 = -4; x = +2
Thus, the oxidation number of Fe in [Fe(CN)₆ ]^4- f is +2.

(ii) Mn in MnO₄^–. Let the oxidation number of Mn in MnO₄^– be x. Writing oxidation number of each atom above its symbol, we get.

Thus, the oxidation number of Mn in MnO₄^– is +7
Predict the oxidation number of the element underlined NaCl, MgSO₄, AlF₃, SiCl₄, PF₃, P₄O₁₀, SF₆, SO₃, HClO₄, Cl₂O₇.
Answer:

Question 27.
What is the maximum and minimum oxidation numbers of N, S and Cl?
Answer:
(i) The highest oxidation number (O.N) of N is +5 since it has five electrons in the valence shell (3s² 2p³ ) and its minimum O.N. is -3 since it can be accept three more electrons to acquire the nearest inert gas (Ne) configuration.

(ii) Similarly, the highest O.N. of S is +6 since it has six electrons in the valence shell (3s² 2p⁴) and its minimum O.N. is -2 since it needs two more electrons to acquire the nearest inert gas (Ar) configuration.

(iii) Likewise the maximum O.N. of Cl is +7 since it has seven electrons in the valance shell (3s² 2p⁵ ) and its minimum O.N. is -1 since it needs only one more electron to acquire the nearest (Ar) Noble gas configuration.

Question 28.
Nitric acid acts only as an oxidising agent while nitrous acid acts both as an oxidising as well as a reducing agent. Why ?
Ans:
(i) Nitric Acid HNO₃ : Here Oxidation number of N is HNO₃ = +5 ; But
Maximum oxidation number of N = +5 ; Minimum oxidation number of N = -3 Since the oxidation number of N in HNO₃ is maximum (+5), therefore it can only decrease by accepting electrons. Hence HNO₃ acts only as an oxidizing agent.

(ii) Nitrous Acid HNO₂ : Here Oxidation number of N in HNO₂ = +3
Maximum oxidation number of N = +5 ; Minimum oxidation number of N = -3 Thus, the oxidation number of N can either increase by losing electrons or can decrease by accepting electrons. Therefore, HNO₂ acts both as an oxidizing as well as a reducing agent.

Question 29.
Write correctly the balanced equations for the following redox reactions using half reaction:
(i) H₂S + Fe³⁺ → Fe²⁺ + S + H⁺
(ii) I^–+IO₃^– + H⁺ → I₂+H₂O
(iii) I^– + O₂ + H₂O → I₂ + OH^–
(iv) Cu(s) + Au⁺ → Au(s) + Cu²⁺
Answer:

Question 30.
Consider the following reactions that produce electricity in the galvanic cell:
(i) 2Fe³⁺(aq) + 2Cl^–(aq) → 2Fe²⁺ (aq) + Cl₂(g)
(ii) 2Cr(s) + 3Cu²⁺ → 3Cu(s) + 2Cr³⁺
Write the anode and cathode reactions for the galvanic cell. Write cell in the usual notation.
Cathode
Answer:

Question 31.
Balance the following reaction :
(i) Cu + NO₃^– → NO₂ + Cu²⁺
Write correctly balanced half cell reactions and overall equations for the following equations by ion electron method:
Answer:

Question 32.
NO₃^– + Bi(s) → Bi³ + NO₂ in acid solution by ion electron method.
Answer:

Question 33.
Cr₂O₇^2- + C₂H₄O^– → C₂H₄O₂ + Cr³⁺ in acid solution by ion electron method.
Answer:

Question 34.
MnO₄ + H₂C₂O₄ → Mn²⁺ + CO₂ in acid solution by ion electron method.
Answer:

Question 35.
A cell is prepared by dipping a zinc rod in 1M ZnSO₄ solution and a lead rod in 1 M Pb(NO₃)₂ solution. The standard electrode a potentials for Pb⁺²/Pb and Zn⁺² /Zn electrode are -0.126 V and -0.763 V respectively. _
(a) How will you represent the cell ?
(b) Write the half cell reactions and the overall cell reaction.
Answer:

Question 36.
Copper dissolves in dilute HNO₃ but not in dilute HCl. Why ? Explain.

Answer:
Electrode potential of Cu²⁺/Cu is higher than H⁺/H₂ and so H⁺ ions cannot oxidize Cu to Cu²⁺ ions and therefore copper does not dissolve in dilute HCl. On the other hand, the electrode potential of NO₃^– ion i.e., NO₃^–/NO electrode is higher than that of copper electrode and hence it can oxidize Cu to Cu²⁺ ion; so copper dissolve in dilute HNO₃.
Thus copper dissolved in dilute HNO₃ due to oxidation of Cu by NO₃^– ions and not by H⁺ions.

1st PUC Chemistry Redox Reactions Five Marks Questions and Answers

Question 1.
Write the following redox reactions using half equations.
(i) Zn(s) + PbCl₂ (aq) → Pb(s) + ZnCl₂(aq)
(ii) 2Fe³⁺ (aq) + 2e^– (aq) →  I₂(s) + 2Fe²⁺ (aq)
(iii) 2Na(s) + Cl₂ (g) →  2NaCl(s)
(iv) Mg(s) + Cl₂(s) → MgCl₂(s)
(v) Zn(s) + 2H⁺ (aq) →  Zn²⁺ (aq) + H₂ (g)
In each of the reactions given above, mention
(i) Which reactant is oxidized ? To what ?
(ii) Which reactant is the oxidizer ?
(iii) Which reactant is reduced ? To what ?
(iv) Which reactant is the reducer ?
Answer:
(i) Zn → Zn²⁺ + 2e^– (oxidation), Pb²⁺ → 2e^– +Pb (reduction) Zn is oxidized to Zn²⁺, Pb²⁺ is reduced to Pb; Pb²⁺ is the oxidizer and Zn is the reducer.

(ii) 2Fe³⁺ + 2e^– → 2Fe²⁺ (reduction), 2l^– → I₂ +2e^– (oxidation)
Fe³⁺ is reduced to Fe²⁺, I^– is oxidized to I₂; I^– is the reducer and Fe³⁺ is the oxidizer.

(iii) 3Na → 2Na⁺ +2e^– (oxidation), Cl₂ + 2e^– > 2Cl^– (reduction)
Na is oxidized to Na⁺ and Cl₂ is reduced to Cl^–; Na is the reducer and Cl₂ is the oxidizer.

(iv) Mg → Mg²⁺ + 2e^– (oxidation), Cl₂ + 2e^– → 2Cl (reduction)
Mg is oxidized to Mg while Cl2 is reduced to Cl ; Mg is the reducer and Cl2 is the oxidizer.

(v) Zn → Zn²⁺ +2e^– (oxidation), 2H⁺ + 2e^– >H₂ (reduction)
Zn is oxidized to Zn²⁺ while H⁺ is reduced to H₂;Zn is the reducer and H⁺ is the oxidizer.

Question 2.
Write the reaction at anode and cathode and the net cell reaction in the following cells. Which electrode would be +ve terminal in each cell ?

Answer:

Question 3.
Mention which element undergoes disproportionate reaction in alkaline media.

Answer:

Question 4.
Calculate emf of the following cell:

Answer:

Question 5.
In the reaction given below^ identify the species undergoing oxidation and reduction:
(i) CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l)
(ii) CH₂ = CH₂(g) + H₂(g) → H₃C – CH₃(g)
(iii) H₂S(g) + O₂(g) → 2S(s) + 2H₂O(1)

Answer:
(i) CH₄ is oxidized to CO₂ while O₂ is reduced to H₂O.
(ii) H₂S is oxidised to S while O₂ is reduced to H₂O.
(iii) CH₂ = CH₂ is reduced to CH₃ – CH₃ while H₂ is oxidized to CH₃ – CH₃.
(iv) Hg²⁺ is reduced to Hg while O^2- is oxidized to O₂.

Question 6.
Using electron-transfer concept, identify the oxidation and reduction in the following redox reactions.
(a) Zn(s) + 2H⁺(aq) → Zn²⁺(aq) + H₂(g)
(b) 2[Fe(CN)₆]^4- (aq) + H₂O₂(aq) + 2H⁺(aq) → 2[Fe(CN)₆]^3- (aq) + 2H₂O(aq)
(c) 2[Fe(CN)₆]^3- (aq) + 2OH^–(aq) + H₂O₂(aq) → 2[Fe(CN)₆]^4-(aq) + 2H₂O(l)
(d) BrO₃^–(aq) + F₂(g) + 2OH^–(aq) → BrO₄^–(aq) + 2F^–(aq) + H₂O(l)
(e) 2NaClO₃(aq) + l₂(aq) → 2NaIO₂(aq) + Cl₂(g)
Answer:
Oxidants : (a) H⁺ (b) H₂O₂, (c) [Fe(CN)₆]^3-, (d) Fe, (e) l₂.
Reductants : (a) Zn, (b) [Fe(CN)₆]^4- , (c) H₂O2, (d) BrO₃^– , (e)NaClO₃

Question 7.
Why do the following reactions proceed differently ?
Pb₃O₄ + 8HCl → 3PbCl₂ +Cl₂ + 4H₂O and
Pb₃O₄ + 4HNO₃   → 2Pb(NO₃)₂ + PbO₂ + 4H₂O
Answer:
Pb₃O₄ is actually a stoichiometric mixture of 2 moles of PbO and one mole of PbO₂, i.e., 2PbO. PbO₂. In PbO₂, lead is present in + 4 oxidation state, whereas in PbO, lead is present in +2 oxidation state. Since +2 oxidation state or Pb is more stable, therefore, PbO₂ acts as an oxidant (oxidizing agent) and hence oxidises OF ions of HCl into Cl₂. Further more, PbO is a basic oxide and hence reacts with HCl to form PbCl₂ and H₂O. Thus the reaction of Pb₂O₄ with HCl can be split into two , reactions, namely, acid-base and redox reaction as shown below :

Since HNO₃ is an oxidizing agent, it does not react with PbO₂ which is also an oxidizing agent. Therefore, no redox reaction occurs between PbO₂ and HNO₃. However, acid-base reaction between PbO and HNO₃ occurs as follows :

2PbO + 4HNO₃ → 2Pb(NO₃ )₂ + 2H₂O

The overall reaction of PbO₃ with HNO₃ can then be written as
2PbO + PbO₂ + 4HNO₃ → 2Pb(NO₃ )₂ + PbO₂ + 2H₂O or
Pb₃O₄+ 4HNO₃ → 2Pb(NO₃ )₂ + PbO₂ + 2H₂O
Thus, it is the passive nature of PbO₂ against HNO₃that makes the reaction of Pb₃O₄ with HNO₃ different from that with HCl.

Question 8.
Explain applications of Redox Reactions.
Answer:
1. Extraction of metals : By using a suitable reducing agent, metal oxides can be ‘ reduced to metals. For example, Fe₂O₃ is reduced to iron in the blast furnace using coke as the reducing agent.

Fe₂O₃(s) + 3C(S) → 2Fe(s) + 3CO(g)

Simialrly, Al₂O₃ is reduced to aluminium by cathodic reduction in an electrolytic cell. Other metals such as lithium, sodium, potassium, magnesium, calcium, etc., are also obtained commercially by electrolytic methods.

2. Electrochemical cells or batteries : Electrochemical cells or batteries based on redox reactions are widely used in our day today life to run a number of small and big gadgets and equipments. For example storage cells are used to supply all the electrical needs of our cars, trucks, buses, trains aeroplanes, etc. Similarly, electrical energy needed in the space capsule is obtained by the reaction of hydrogen and oxygen in fuel cells which are electro chemical cells using oxygen and hydrogen electrodes.

3. Photosynthesis : Green plants convert carbon dioxide and water into carbohydrates in presence of sunlight. This reaction is called Photosynthesis and is sensitized by chlorophyll.

During this reaction, CO₂ is reduced to carbohydrates while water is oxidized to oxygen. The energy needed for the reaction is provided by sunlight.

This reaction is a source of food for plants and animals. It also maintain a constant supply of 21% of O₂ by volume in the atmosphere needed for combustion of fuels and breathing of a living creatures in the world.

4. Supply of energy : The energy required for our daily needs is obtained by oxidation of fuels. For example, oxidation of fuels such as wood, gas, kerosene, petrol, etc., produces a large amount of energy which we need for various purposes in our daily life.
Fuels (wood, petrol, kerosene, gas) + O₂ → CO₂ + H₂O + other products + Energy

Human body also needs energy for proper functioning. This is obtained by the oxidation of glucose in our body to CO₂ and water.

5. Production of chemicals : Many chemicals of our daily needs such as caustic soda, chlorine, fluorine, etc, are produced by electrolysis which is based on redox reaction.

6. Quantitative analysis : Redox reactions are very useful in quantitative analysis by redox titrations. These titrations involve the reactions between oxidizing and reducing agents and help in estimating the amount of unknown substances in solutions.

Question 9.
Balance the following equations in acidic medium by oxidation number

Answer:

Question 10.
Balance the following equation by ION-Electron method :
Zn(s) + NO₄⁺ → Zn²⁺ (aq) + NH₄⁺ (aq) + H₂O(l)
Answer:

Question 11.
Split the following redox reaction in the oxidation and reduction half reactions:
(a) 2K(s) + Cl₂(g) >2KCl(s)
(b) 2Al(s) + 3Cu²⁺(aq) >2Al³⁺(aq) + 3Cu(s)
Answer:
(a) Let us write the oxidation numbers of the atoms of all the reactants and products taking part in reaction.

(b) Let us write the oxidation numbers of the atoms of all the reactants and products taking part in the reaction.
Increase in Oxidation Number

Question 12.
Balance the following reaction by ION-ELECTRON method Cl₂(g) + OH^– → Cl^– (aq) + CIO₃^– (aq) + H₂O (in basic medium)
Answer:
Cl₂(g) + OH^– → Cl^– (aq) + CIO₃^– (aq) + H₂O

Cl₂(g) + 6H₂O(l) → 2ClO₃^–(aq) (… Go for balancing oxygen is a abasic media odd off on RHS )
Cl₂(g) + 6H₂O(l) + 12OH^– → 2ClO₃^–(aq) + 12H₂O(l)
Cl₂(g) + 12OH^– (aq) → 2ClO₃^–(aq) + 6H₂O(l) (now balance e-)
Cl₂(g) I +12OH^– (aq) → 2ClO₃^–(aq) + 6H₂O(l) + 10e^– . ..(1)
Reduction half-reaction
Cl₂(g) → Cl^–(aq)
Cl₂(g) → 2Cl^–(aq)
Cl₂(g) + 3e → 2Cl^–(aq) …(2)
Multiply equation no. (2) by 5 to equalize electrons
Add both the half-reactions

Question 13.
Write the over all net ionic reaction for the following change if the half reactions are correctly balanced: Cl^– ion is oxidized to Cl₂ by MnO₂ in acidic solution: Chloride ion is oxidized to Cl₂ by MnO₄^–(in acid solution)
Answer:
The skeletal equation is

Where ox. no. of chlorine changes from -1 in Cl ion to O in Cl₂

Question 12.
A cell is prepared by dipping a chromium rod in 1 M Cr₂(SO₄)₃ solution and an ion rod in 1 M FeSO₄ solution. The standard reduction potentials of chromium and iron electrodes are -0.75V and -0.45 V respectively.
(a) What will be the cell reaction ?
(b) What will be the standard EMF of the cell ?
(c) Which electrode will act as anode ?
(d) Which electrode will act as cathode ?
Answer:
The two half cell reduction equations me :

Fe²⁺(aq) + 2e^– → Fe(s);E° =-0.45 V …(i)
Cr³⁺(aq) + 3e^– → Cr(s);E° = -0.75V …(ii)

Since Cr³⁺ / Cr electrode has lower reduction potential therefore it acts as the anode while Fe²⁺ /Fe electrode with higher electrode potential acts as the cathode.

To equalize the number of electrons, multiply Eq. (i) by 3 and Eq. (ii) by 2. But do not multiply their E° values. Thus,

3Fe²⁺ (aq) + 6e^– → 3Fe(s); E° = -0.45V .. .(iii)
2Cr³⁺(aq) + 6e^– → 2Cr(s) ; E° =-0.75V …(iv)

To obtain equation for the cell reaction, subtract Eq. (iv) from Eq. (iii), we have,
2Cr(s) + 3Fe²⁺(aq) → 2Cr³⁺(aq) + 3Fe(s)
E°_cell = -0.45-(-0.75V) = +0.30V Thus, the EMF of the cell = + 0.30V

Question 13.
Write the net ionic equation for the reaction of potassium dichromate (VI), K₂Cr₂O₇ with sodium sulphate, Na₂SO₃, in acid solution to give chromium (III) ion and sulphate ion.
Answer:
Step-1: Write the skeleton equation for the given reaction.

Step – 2 : Find out the elements which undergo a change in oxidation number (O.N.) O.N. decreases by 3 per Cr. atom

Here, O.N. of Cr decreases from +6 in Cr₂O₇^2- to +3 in Cr³⁺ while that of S increases from +4 SO₃^-2 to +6 in SO₄^2-
Step – 3 : Balance increase / decrease in O.N. since the total increase in O.N. is 2 and decrease is 6, therefore, multiply SO₃^2- on L.H.S. and SO₄^2- on R.H.S. of Eq. (ii) by 3. Combining steps 2 and 3, we have,

Step – 7 : Balance O atoms by adding H₂O molecules.

Step – 7 : Balance H atoms by adding H⁺

Thus, Eq. (v) represents the correct balanced equation.

Question 14.
Permanganate ion react with bromide ion in basic medium to give manganese dioxide and bromate ion. Write the balance chemical equation for the reaction.
Answer:
Step – 1: Write the skeletal equation. The skeletal equation for the given reaction is :

Step – 2 :
Find out the elements which undergo a change in oxidation number (O.N.) O.N. increases by 6 per Br atom

Here, O.N. of Br inceases from – 1 Br^– to +5 in BrO₃^–, therefore, Br^– acts as reductant. Further, O.N. of Mn decreases from +7 in MnO₄^– to +4 in MnO₂, therefore, MnO₄^– acts as oxidant.

Step – 3 : Balance O atoms by adding H₂O molecules.

Step – 4 s Balance H atoms by adding H₂O and OH^– ions since the reaction occurs in basic medium, therefore, add 2H₂O to L.H.S. and 2OH^– to R.H.S. of Eq. (iv), we have,

Question 15.
Write the half reactions for the following redox reactions.
(a) Fe²⁺(aq) + 2I^–(aq) → 2Fe²⁺(aq) + I₂(aq)
(b) Zn(s) + 2H⁺(aq) → Zn²⁺(aq) + H₂(g)
(c) Al(s) + 3Ag⁺(aq) → Al³⁺(aq) + 3Ag(s)
Answer:

Question 16.
Balance the equation, by ion electron method.
AS₂S₃(S) + NO₃^–(aq) + H⁺ (aq) → AsO₄^3-(aq) + S(s) + NO(g) + H₂(l)
Answer:
Step 1 : To identify the atoms whose oxidation numbers have undergone a change. Writing the oxidation number of each atom above its symbol, we have

Step 2:

Step 3 : To balance the oxidation half Eq. (i)
(a) Balance all the atoms other than H and O. Multiply AsO₄^3- by 2 and S by 3 on RHS of Eq. (i) we have,

(c) Balance charge by adding H+ ions. The total charge on RHS of Eq. (iv) is -16 and zero the LHS therefore, add 16H+ to RHS of Eq. (iv) we have,

(d) Balance O atoms by adding H₂O molecules.

The H-atoms get automatically balanced. Thus Eq. (vi) represents the balanced oxidation half equation.

Step 4 : To balance the reduction half Eq. (ii)
(a) Balance oxidation number by adding electrons.

(b) Balance charge by adding H+ ions.

(c) Balance H+ by adding H20

Thus, Eq. (ix) represents the balanced reduction half equation Eq. (ix) by 10 and Eq,
(vi) by 3 and (ix) 10 + (vi) x 3

Step 5 :

Question 17.
Permanganate (VII) ion, in basic solution oxidizes iodide ion 1- to produce molecular iodine (I₂) and manganese (IV) oxide (MnO₂). Write a balanced ionic equation to represent this redox reaction.
Answer:
Step 1 s Write pie skeletal equation for the given reaction.

Step 2 : Write the O.N. of all the elements above their respective symbols.

Step 4 : To balance oxidation half Eq. … (ii)
(a) Balance all atoms 2I^–(aq) → I₂(s) … (iv)
(b) Balance O.N. by adding electrons.
2I^–(aq) → I₂(s) + 2e^– …(v)
Charge on either side of Eq(v) is balanced. Thus, Eq. (v) represents the balanced oxidation half equation.

Step 5 : Balance the reduction half equation (iii)
Balance O.N. by adding electrons.

Step 6: To balance the electrons lost in Eq. (v) and gained in Eq. (viii) Equation (v) x 3 + Equation (viii) x 2 we have,

This represents are final balanced redox equation.

Question 18.
In passing chlorine gas through a concentrated solution of alkali, we get chloride and chlorate ions. Obtain balanced chemical equation for this reaction by ion -electron method.
Answer:
Step 1: Write the skeletal equation for the given reaction.

Step 2 : Write the ON of all the elements above their respective symbols O.N. of Cl increases by 5 per Cl atom.

O.N. of Cl decreases by 1 per Cl atom Total increase = 2 x 5 = 10 Total decrease = 2 x -1 = -2

Step 3 : Find out the oxidant and the reductant and split the skeletal Eq (i) into two half reactions.

Step 4 : To balance the reduction half equation (ii). (a) Balance all atoms.
Cl₂(aq) →2Cl^–(aq) … (iv)
(b) Balance oxidation number by adding electrons.
Cl₂(g) + 2e^– →2Cl^–(aq) … (v)
represents the balanced reduction half reactions.

Step 5 : To balance the oxidation half equation (iii)
(a) Balance all atoms Cl₂(g) »2ClO₃^–
(b) Balance ON by adding electrons.
Cl₂(g) → 2ClO₃^–(aq) + 10e^– … (vi)
(c) Balance charge by adding OH” ions
Cl₂(g) + 120H^–(aq) → 2ClO₃^–(aq) + 10e^– … (ix)
(d) Balance O atoms, the RHS of Eq. (viii) contains six O atoms but on the LHS there are 12. Therefore, add 5H₂O to the RHS, we have

Eq (ix) represents the balanced oxidation half equation.

Step 6 : (v) x 5 + (ix) we have

This represents the final balanced redox equation.

Question 19.
Suggest a scheme of classification of the following redox reactions.
(a) N₂(g) + O₂(g) →2N(Xg)
Ob) 2Pb(NO₃)₂(s) → 2PbO(s) + 2NO₂(g) + 1/2 O₂(g)
(c) NaH(s) + H₂O(1)→  4NaOH(aq) + H₂(g)
(d) 2NO₂(g) + 20H^–(aq) → NO₂^–(aq) + NO₃^– (aq) + H₂O(l)
Answer:
(a)
In this reaction, the compound nitric oxide is formed by combination of elemental substances like nitrogen and oxygen. Since the oxidation number of nitrogen increases from 0 to +2 and of oxygen decreases from 0 to -2 therefore, it is a combination redox reaction.

(b)

In this reaction, lead nitrate decomposes to form three products, viz, lead oxide, nitrogen dioxide and oxygen. Since the oxidation number of nitrogen decrease from +5 in lead nitrate to +4 in NO2 in O2, therefore, it is a decomposition redox reaction.

(c)

In this reaction, hydrogen of water has been displaced by hydride ion to form dihydrogen gas. Therefore, it is a displacement reaction. Since in this reaction, the oxidation number of hydrogen increases from -1 in hydride ion to zero in dihydrogen gas and that of hydrogen decreases from +1 in water to zero in dihydrogen, therefore, it is a displacement redox reaction.

(d)

This is a disproportionation reaction since here the oxidation state of nitrogen decreases from +4 in NO₂ to +3 in NO₂^– ion, as well as increases from +4 in NO₂ to +5 in NO₃ ion.

Question 20.
Calculate the oxidation number of the element underline in each of the following cases,
(a) Al in Al₂O₃
(b) P in P₂O₅
(c) S in Na₂S₂O₃
(d) Cl in NaClO₃
(e) Mn in KM_nO₄
(f) HA₄Cl₄
(g) Na₂PdCl₄
(h) K₄MO₂Cl₈
(i) ClO^–
(j) Si0₃2^–
(k) H₂PO₄^–
(1) Cr₂O₇2^–
(m) H₂PO₄^–
Answer:
Solution : The rule used here is that the algebraic sum of the oxidation numbers of all the atoms a molecule is zero.

b) P₂O₅ : 2 x (oxidation no. of P) + 5(-2) = 0
oxidation of P = pp = +5

c) Na₂S₂O₃ : 2(+l) + 2(oxidation no. of S) + 3(-2) = 0
2(oxidation no. of S) = 4

d) NaClO₃ : 1(+1) + (oxidation no. of Cl) +3 (-2) = 0
oxidation no. of Cl = +6 – 1 = +5

e) KMnO₄ : 1(+1) + (oxidation no. of Mn) + 4(-2) = 0
+1 + (oxidation no. of Mn) – 8 =0
∴ oxidation no. of Mn = + x7
Answer:
Solution : The rule used here is that the algebraic sum of the oxidation numbers of all the atoms in an ion is equal to the net charge on the ion.

f) HA₄Cl₄ 1(ON of H) + 1C (ON of A4) + (ON of Cl) = 0
(+1) + x + 4(-l) = 0 => l + x-4 = 0 => x = +3

g) Na₂PdCl₂ = 2(+l) + x + 4(-l) = 0 => 2+x-5=0 => x = +2

h) x be ON to be find
K₄MO₂Cl₈ = 4(+l) + (x)2 + 8(-l) = 0
4 + 2x – 8 = 0 => 2x – 4 = 0 => x = +2

Question 21.
What is oxidation number of sulphur in the following molecules / ions (n) sinH₂S sin SO₄^2- sinH₂SO₄
Answer:
(i) The oxidation number of Hydrogen is +1, and s = x than

(ii) SO₄^2- let x be ON of s ; Oxidation Number of oxygen is -2

(iii) H₂SO₄ let x, +1, -2 be on of S, H and O

Question 22.
Find the oxidation number of the underlined atoms.
(a) CCl₄
(b) CH₄
(C) ClO₃^–
(d) BrF₃
(e) Na₂ B₄O₇
(f) HClO₃
(g) HPO₂ ^–
(h) Fe₃ O₄
Answer: