CBSE Class 10 Science Term 1 Exam 2021-22: Important Assertion Reason Questions with Answer Key Here for Tomorrow's Paper

CBSE Class 10 Science Term 1 Exam will be held on 2nd December, 2021. Here are important assertion and reason questions for Class 10 Science (chapter-wise) to prepare for the term 1 exam. All questions are prepared by experienced teachers.

Created On: Dec 1, 2021 18:32 IST
Modified On: Dec 2, 2021 13:27 IST
CBSE Class 10 Science Assertion Reason Questions for Term 1 Exam
CBSE Class 10 Science Assertion Reason Questions for Term 1 Exam

CBSE Class 10 Science Term 1 Exam 2021-22: After the Social Science paper, next major paper for Class 10 students will be of Science. CBSE Class 10 Science Term 1 Paper 2021 will be held on 2nd December. We have provided here some very important assertion-reason questions for Class 10 Science in PDF. You can read the chapter-wise questions to prepare for your Science paper. All the questions are prepared by experienced teachers. Answer Key for all questions is also provided. So, practice these important MCQs to score well in the CBSE Class 10 Science Paper 2021-22 (Term 1). New*

CBSE Class 10 Science Term 1 Question Paper 2021 (with Answer Key)

CBSE Class 10 Science Term 1 Exam Analysis and Students' Feedback

CBSE Class 10 Science Assertion-Reason Questions (Chapter-wise)

Chapter 1 - Chemical Reactions And Equations

In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as: 

(a) Both A and R are true and R is the correct explanation of A.

(b) Both A and R are true but R is not the correct explanation of A.

(c) A is true but R is false.

(d) A is false but R is true.

Also Check: CBSE Class 10 Science Best Resources for Quick Revision and Full Marks In Term 1 Paper

1.Assertion (A) : Decomposition of vegetable matter into compost is an example of exothermic reactions.

Reason (R) : Exothermic reaction are those reactions in which heat is evolved.

2.Assertion (A) : When HCl is added to zinc granules, a chemical reaction occurs.

Reason (R) : Evolution of a gas and change in colour indicate that the chemical reaction is taking place.

3.Assertion (A) : Calcium carbonate when heated gives calcium oxide and water.

Reason (R) : On heating calcium carbonate, decomposition reaction takes place.

4.Assertion (A) : Brown fumes are produced when lead nitrate is heated.

Reason (R) : Nitrogen dioxide gas is produced as a by product due to the decomposition of lead nitrate.

5.Assertion (A) : White silver chloride turns grey in sunlight.

Reason (R) : Decomposition of silver chloride in presence of sunlight takes place to form silver metal and chlorine gas.

6.Assertion (A): Pungent smelling gas is produced when sulphur burns in air.

Reason (R) : Sulphur trioxide is formed on reaction of sulphur with oxygen.

7.Assertion (A) : In a reaction of copper with oxygen, copper serves as a reducing agent.

Reason (R) : The substance which gains oxygen in a chemical reaction acts as a reducing agent.

8.Assertion (A) : In electrolysis of water, the volume of hydrogen liberated is twice the volume of oxygen ……formed.

Reason (R) : Water (H,0) has hydrogen and oxygen in the ratio of 1:2 by volume.

9.Assertion (A): Corrosion of iron is commonly known as rusting.

Reason (R) : Corrosion of iron occurs in presence of water and air.

10.Assertion (A) : The balancing of chemical equations is based on law of conservation of mass.

Reason (R) : Total mass of reactants is equal to total mass of products.

Best Exam Writing Tips to Score Full Marks in Class 10 Science Term 1 Paper

CBSE Class 10 Science Important Questions (MCQs) for Last Minute Revision for Term 1 Exam 

11.Assertion (A): In a balanced chemical equation, total mass of the reactants is equal to the total mass of the products.

Reason (R): Mass can neither be created nor destroyed during a chemical change.

12.Assertion (A): Iron articles are painted so as to prevent them from rusting.

Reason (R): When the surface of iron is coated with paint, its surface does not come in contact with oxygen and moisture therefore rusting does not take place.

13.Assertion (A) : Chemical reaction changes the physical and chemical state of a substance.

Reason (R) : When electric current is passed through water (liquid), it decomposes to produce hydrogen and

oxygen gases.

14.Assertion (A): When calcium carbonate is heated, it decomposes to give calcium oxide and carbon dioxide.

Reason (R): The decomposition reaction takes place on application of heat, therefore, it is an endothermic reaction.

15.Assertion (A): Zinc reacts with sulphuric acid to form zinc sulphate and hydrogen gas and it is a displacement reaction.

Reason (R): Zinc reacts with oxygen to form zinc oxide.

16.Assertion (A): Chips manufacturers usually Ilush bags of chips with gas such as nitrogen to prevent the chips from getting oxidised.

Reason (R): This increase the taste ot the chips and helps in their digestion.

17.Assertion (A): Exposure of silver chloride to sunlight for a long duration turns grey due to the formation of silver by decomposition of silver chloride.

Reason (R): In this process, sublimation of silver chloride takes place.

18.Assertion (A): Rusting of iron metal is the most common form of corrosion.

Reason (R): The effect of rusting of iron can be reversed if they are left open in sunlight.

19.Assertion (A): AgBr is used on photographic and X-ray film.

Reason (R): AgBr is photosensitive and changes to Ag and bromine in presence of sunlight and undergoes decomposition reaction.

20.Assertion (A): Magnesium ribbon keeps on burning in atmosphere of nitrogen.

Reason (R) : Magnesium reacts with nitrogen to form magnesium nitride and this reaction is combination reaction.

Answer Key:

Q. No.


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Assertion and Reason questions for all chapters of Class 10 Science for Term 1 Exam can be downloaded from the following link:

CBSE Class 10 Science Assertion & Reason Questions for Term 1 Exam 2021-22 

Also Check: CBSE Important Practice Questions for Class 10 Science Term 1 Exam (By CBSE Board)


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  • Praneet kumarDec 1, 2021
    not a good one all questions are copied from other sites
  • Piyush KumarDec 1, 2021
    nice keep going
    Praneet kumarDec 1, 2021
    wtf is nice here all ques are copied
  • ved patelDec 1, 2021
    it was good
  • ved patelDec 1, 2021
    loved this pdf
    Praneet kumarDec 1, 2021
    haa sale shadi kr le isse
  • ved patelDec 1, 2021
    very nice