Chemical Reaction

Physical change is a temporary or reversible change in which no new substances are formed. A chemical change is a permanent and usually irreversible change in which new substances with different properties are formed. This note gives us the information on physical change, chemical change , and chemical reaction.

Summary

Physical change is a temporary or reversible change in which no new substances are formed. A chemical change is a permanent and usually irreversible change in which new substances with different properties are formed. This note gives us the information on physical change, chemical change , and chemical reaction.

Things to Remember

  • Physical change is a temporary or reversible change in which no new substances are formed.
  • A chemical change is a permanent and usually irreversible change in which new substances with different properties are formed.
  • Chemical changes are permanent changes.
  • Physical changes are temporary a change.
  • The chemical reaction which is expressed by using molecular formulae of reactants and products is called chemical equation
  • The chemical reaction which is expressed in terms of full names of reactant and product molecules is called word equation. 

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Subjective Questions

Q1:

Explain in short any three advantages of accounting.


Type: Short Difficulty: Easy

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Answer: <p>The advantages of accounting are explained below:-</p> <ol><li><strong>Accessing the performance of the business</strong><br>Accounting keeps a proper and systematic record of all business transactions. The income statement is prepared with these records and we are able to know the profit earned and the loss suffered by the business.<br><br></li> <li><strong>Documentary evidence</strong><br>Accounting records can be used as an evidence in the court to substantiate the claim of the business. These records are based on documentary proof. In this way, the court accepts these records as evidence.<br><br></li> <li><strong>Facilitating the sale of the business</strong><br>The position statement of the business shows the value of assets and liabilities of the business. Accounting facilities in the calculation of the consideration for which the business should be sold.</li> </ol><p></p>

Q2:

Define accounting.


Type: Very_short Difficulty: Easy

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Answer: <p>Accounting is an act of identifying, classifying, recording, summarising and interpreting business transactions of financial nature.</p>

Q3:

Mention two advantages of accounting.


Type: Very_short Difficulty: Easy

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Answer: <p>Any two advantages of accounting are:-</p> <ol><li>Knowledge of financial position</li> <li>Documentary evidence</li> </ol>

Q4:

State any two functions of accounting.


Type: Very_short Difficulty: Easy

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Answer: <p>Any two functions of accounting are:</p> <ul><li>To ascertain profit or loss</li> <li>To depict the financial position</li> </ul>

Q5:

Explain in short any three objectives of accounting. 


Type: Short Difficulty: Easy

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Answer: <p>Any three objectives of accounting are:</p> <ul><li><strong>To analyze and interpret the financial information</strong><br>It analyzes and interprets the result of the business to draw conclusions with the help of such conclusions the parties concerned in the business can have full information about its profitability and financial position.<br><br></li> <li><strong>To help in determination of tax liability</strong><br>Business has to pay different types of tax to the government. It provides the financial information to tax authorities to determine tax liability.<br><br></li> <li><strong>To depict the financial position</strong><br>A concern, whether trading or non-trading should know it&rsquo;s true financial positions. For this purpose, it prepares a balance sheet at the end of every year which informs about its positions of assets, liabilities and capital and reflects the economic strength and weaknesses of the business.</li> </ul>

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Chemical Reaction

Chemical Reaction

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Physical change

Physical change is a temporary or reversible change in which no new substances are formed. Examples:

  • Lightening of an electric bulb.
  • Magnetizing an iron nail.
  • Preparing a solution.
  • Changing of ice into the water and water vapour in heating.
  • Making of different objects from the soil.

Characteristics of physical changes

  • Physical changes are temporary a change.
  • They are reversible change.
  • In these changes, no new substances are formed.
  • In these changes, only physical properties are changed but chemical compositions are not changed.

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Chemical change

A chemical change is a permanent and usually irreversible change in which new substances with different properties are formed.

Characteristics of chemical change

  • Chemical changes are permanent changes.
  • They are usually irreversible changes.
  • In this change, new substances are formed.
  • Rusting of iron.
  • Burning magnesium ribbon in air to form magnesium oxide.

Differences between physical and chemical changes

Physical change Chemical change
No new substances are formed. New substances are formed.
It is a temporary change in which chemical composition of the substance remains the same. It is a permanent change in which chemical composition of the substance changed.
Change in energy is not usually seen in it. Change in energy is visible.
Change in mass is not seen. E.g., dissolving the salt in water Change in mass is seen in it, e.g., rusting of iron.
Only the physical properties like colour, taste or state are changed. Chemical, as well as physical properties, are changed.
It is usually reversible. It is usually irreversible.

Chemical reaction

The process by which a chemical change takes place is called as a chemical reaction. Those substances that take part in a chemical reaction are called reactants. Those substances which are formed by a chemical reaction are called products.

Word equation

The chemical reaction which is expressed in terms of full names of reactant and product molecules is called word equation. For example, Hydrogen reacts with oxygen to produce water.

Chemical Reaction Hydrogen + oxygen→Water
Chemical Reaction Hydrogen + oxygen→Water

Hydrogen + oxygen→Water

(Reactants) (Products)

Chemical equations

The chemical reaction which is expressed by using themolecular formula of reactants and products is called chemical equation. The chemical equation is also called formula equation.

2 H2 + O2→2 H2O

Lesson

Chemical Reaction

Subject

Science

Grade

Grade 9

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