Class 10 Science Chapter 1 Chemical Reactions and Equations Concept Clarity MCQs with Answers

 Practice these 10 Concept Clarity MCQs to strengthen your understanding of Chapter 1. These questions are designed according to the CBSE syllabus.

Concept Clarity MCQs

Q1. Which of the following observations do not help us determine whether a chemical reaction has taken place?

a) change in state (b) change in colour (c) change in quantity (d) change in temperature 

Q2. CaO + H₂O  --> Ca(OH)₂ + Heat, Identify the type of reaction

a) Combination reaction (b) Decomposition reaction (c) Exothermic reaction (d) Both a and c 

Q3. ...................... is used for whitewashing walls.

a) Quick lime (b) Slaked lime (c) Soda lime (d) none of these 

Q4. Ca(OH)₂ reacts slowly with the ................ in air to form a thin layer of calcium carbonate on the walls.

a) Oxygen (b) Nitrogen (c) Carbon dioxide (d) All of these 

Q5. Which of the following gives a shiny finish to the walls after whitewashing.

a) Carbon dioxide (b) Calcium hydroxide (c) Calcium oxide (d) Calcium carbonate

Q6. Decomposition of vegetable matter into compost is an example of which type of reaction?

a) Exothermic reaction (b) Endothermic reaction (c) Displacement reaction (d) none of these

Q7. ......................combines with oxygen in the cells of our body to provide energy.

a) Carbon dioxide (b) Glucose (c) Starch (d) food

Q8. Ferrous sulphate crystals decompose to ferric oxide and ..............

a) Sulphur dioxide (b) Sulphur trioxide (c) both a and b (d) none of these 

Q9. Decomposition of which of the following compounds is involved in the cement industry?

a) Ferrous sulphate (b) Sodium carbonate (c) Calcium carbonate (d) All of these 

Q10. Decomposition of Lead nitrate produces which of the following?

a) Oxygen gas (b) Nitrogen dioxide (c) Lead oxide (d) All of these  

Q11. A white solid 'X' turns grey on exposure to sunlight due to the formation of silver. Identify 'X'.

a) Silver nitrate (b) Silver chloride (c) Silver bromide (d) Lead nitrate

Q12. A metal 'X' is dipped in blue copper sulphate solution. After some time, the solution turns light green and a reddish-brown coating appears on the metal. Identify 'X'.

a) Copper (b) Silver (c) Iron (d) Gold

Q13. Two aqueous solutions, 'X' and barium chloride, are mixed. A white insoluble precipitate is formed. Identify 'X'.

a) Sodium chloride (NaCl)
b) Copper sulphate (CuSO₄)
c) Sodium sulphate (Na₂SO₄)
d) Calcium carbonate (CaCO₃)

Q14. In the reaction

$$\mathbf{ \; \; \; heat}$$

$$\mathbf{<b>C</b>}\mathbf{u}\mathbf{O}+{\mathbf{H}}_{\mathbf{2}}\stackrel{}{ \; \; ------\to }\mathbf{ C}\mathbf{u}+{\mathbf{H}}_{\mathbf{2}}\mathbf{O}$$

which of the following statements is correct?

a) Copper(II) oxide is oxidised and hydrogen is reduced.
b) Both CuO and H₂ are oxidised.
c) Copper(II) oxide is reduced and hydrogen is oxidised.
d) Both CuO and H₂ are reduced.

Q15. Which one of the following reactions is a redox reaction?

a) Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
b) Fe + CuSO₄ → FeSO₄ + Cu
c) ZnO + C → Zn + CO
d) CaO + H₂O → Ca(OH)₂

Q16. Food containing oils and fats develops an unpleasant smell after being left open because:

a) The food absorbs water.
b) The fats and oils undergo oxidation.
c) The food freezes.
d) The food evaporates.

Q17. Which of the following helps slow down rancidity?

a) Storing food in open containers
b) Keeping food in airtight containers
c) Heating food repeatedly
d) Exposing food to sunlight

Q18. Which substance is commonly added to foods containing fats and oils to reduce oxidation?

a) Catalysts
b) Indicators
c) Antioxidants
d) Acids

Q19. Which of the statements about the reaction below are incorrect?

CuO(s) + H₂(g) → Cu(s) + H₂O(l)

(i) Copper oxide is getting reduced.
(ii) Hydrogen is getting oxidised.
(iii) Copper is getting oxidised.
(iv) Water is acting as the reducing agent.

Options:

• (a) (iii) and (iv)
• (b) (i) and (ii)
• (c) (ii) and (iii)
• (d) (i), (iii) and (iv)

Q20. Which of the following statements about the reaction below are correct?

Fe₂O₃(s) + 2Al(s) → Al₂O₃(s) + 2Fe(s)

(i) Iron(III) oxide is getting reduced.
(ii) Aluminium is getting oxidised.
(iii) Aluminium acts as the reducing agent.
(iv) Iron is getting reduced.

Options:

(a) (i), (ii), (iii) and (iv)
(b) (i), (ii) and (iv) only
(c) (i) and (iii) only
(d) (ii) and (iv) only

🧠 TopperGuru1 Concept Check

Before checking the answer key, ask yourself these two questions for every MCQ:

✅ Why is the correct option right?

✅ Why are the other three options wrong?

If you can explain both, your concept is truly clear. If not, revise the related NCERT concept and try again.

Remember: Real learning happens when you understand the reason, not when you memorize the answer.

✅ Answer Key

1. (c) 2. (d) 3. (b) 4. (c) 5. (d) 6. (a) 7. (b) 8. (c) 9. (c) 10. (d) 11. (b) 12. (c) 13. (c) 14. (c) 15. (c) 16. (b) 17. (b) 18. (c) 19. (a) 20. (a)