NCERT Class 10 Chapter 1 Chemical Reaction and Equation CBSE Board Sample Problems Short Answer (For CBSE, ICSE, IAS, NET, NRA 2022)

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2 g of ferrous sulphate crystals are heated in a dry boiling tube.

i) List any two observations.

ii) Name the type of chemical reaction takes place.

iii) Write the chemical equation for the reaction.


i) Reddish brown solid is obtained, smell of burning sulphur.

ii) Decomposition reaction.



What do you mean by rancidity? Mention any two ways by which rancidity can be prevented.


The process in which taste and smell of food gets spoiled is called rancidity . It happens due to oxidation.

Prevention from rancidity:

I) Antioxidants are added to fatty acids to prevent oxidation. Eg, chips are packed

II presence of nitrogen gas which prevents spoilage by oxidation.

III) Food should be kept in airtight container in refrigerator.


No chemical reaction takes place when granules of a solid, A, are mixed with the powder of another solid, B. However when the mixture is heated, a reaction takes place between its components. One of the products, C, is a metal and settles down in the molten state while the other product, D floats over it. It was observed that the reaction is highly exothermic.

(i) Based on the given information make an assumption about A and B and write a chemical equation for the chemical reaction indicating the conditions of reaction, physical state of reactants and products and thermal status of reaction.

(ii) Mention any two types of reaction under which above chemical reaction can be classified.


(j) Based on the given information, solid A can be assumed to be manganese dioxide () and solid B can be assumed to be aluminium powder (Al) .

When manganese dioxide is heated with aluminium powder, the following reaction takes place: The reaction is highly exothermic reaction and a lot of heat is evolved.

(ii) (a) Displacement reaction (b) Exothermic reaction (c) Redox reaction


When a green iron salt is heated strongly, its colour finally changes to brown and odour of burning sulphur is given out.

a) Name the iron salt.

b) Name the type of reaction that takes place during heating of iron salt.


a) Ferrous sulphate

b) Decomposition Reaction


What is an oxidation reaction? Identify in the following reaction

i) The substance oxidized

ii) The substance reduced:


Oxidation reaction is defined as reaction in which addition of oxygen to a substance or removal of hydrogen from a substance takes place.

i) The substance oxidized is: Carbon (C)

ii) The substance reduced is: Zinc oxide (ZnO)


On adding dilute HCI to copper oxide powder the solution formed is blue green in colour. Predict the new compound formed which imparts a blue green colour to the solution.


The new compound formed is cupric chloride. It imparts a blue green colour to the solution.


When potassium iodide solution is added to a solution of lead nitrate in a test-tube, a precipitate is formed.

i) What is the colour of this precipitate? Name the compound precipitated.

ii) Write the balanced chemical equation for this reaction.

iii) List any two types of reaction in which this reactions can be placed.


i) Yellow colour precipitate is formed, compound precipitated is lead Iodide.


iii) Double decomposition and precipitation reaction


While Abhi was about to burn magnesium ribbon in the chemistry laboratory, the teacher asked him to clean the ribbon with the sand paper before burning it. What could be the reason for the above instruction by the teacher? After burning the magnesium ribbon, Abhi obtained a white coloured residue. Name this residue. What type of chemical reaction has occurred? Write a balanced chemical equation to explain the reaction.


Magnesium reacts with atmospheric oxygen to develop a layer of magnesium oxide. This layer does not allow the underlying magnesium to undergo combustion.

Magnesium oxide, Combination reaction.


A group of students carried out electrolysis of acidified water in the laboratory. By the end of the experiment two gases were collected in the test tubes at both the electrodes.

(a) Name the gases collected at cathode and the anode respectively.

(b) The gas collected in one test tube is double the volume of gas collected in the other. Name this gas. Give reason for your answer.

(c) Write a balanced chemical equation to represent the electrolysis of water.


a) Cathode - Hydrogen, anode - Oxygen

(b) The gas is hydrogen. This is because water is formed by the chemical combination of hydrogen and oxygen in the ratio 2: 1 by volume, so it decomposes in the same ratio.



Varun carried out the chemical reaction between aqueous solutions of barium chloride and sodium sulphate. Write any one prominent observation that Varun would have recorded. Name the type of chemical reaction that has occurred and define it. Write a balanced chemical equation to explain above reaction.


White precipitates are seen due to the formation of Barium sulphate. Double displacement reaction has occurred . It is a reaction in which reactants in their aqueous solutions mutually exchange their ions to form products.

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