10 Assertion-Reason (A-R) questions with answers from Class 10 Science Chapters: "Chemical Reactions and Equations" and "Acids, Bases and Salts". These are useful for practice and aligned with CBSE exam patterns.
✅ Instructions:
For each question, choose the correct option:
(A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
(B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
(C) Assertion is true, but Reason is false.
(D) Assertion is false, but Reason is true.
🧪 From Chapter: Chemical Reactions and Equations
1.
Assertion: Silver chloride turns grey in sunlight.
Reason: It forms silver and chlorine gas on decomposition.
✅ Answer: A
2.
Assertion: Magnesium ribbon should be cleaned before burning.
Reason: The layer of magnesium oxide on ribbon prevents it from burning.
✅ Answer: A
3.
Assertion: Rusting of iron is a physical change.
Reason: A new substance, iron oxide, is formed.
✅ Answer: D
(Because rusting is a chemical change, not physical.)
4.
Assertion: In a displacement reaction, a more reactive metal replaces a less reactive metal.
Reason: Displacement reactions are a type of redox reactions.
✅ Answer: A
5.
Assertion: The reaction between nitrogen and hydrogen to form ammonia is reversible.
Reason: Energy is absorbed during the reaction.
✅ Answer: C
(The reaction is reversible, but it is exothermic, not endothermic.)
🧪 From Chapter: Acids, Bases and Salts
6.
Assertion: Acetic acid does not dissociate completely in water.
Reason: Acetic acid is a weak acid.
✅ Answer: A
7.
Assertion: Sodium hydroxide solution turns red litmus blue.
Reason: Bases turn red litmus blue.
✅ Answer: A
8.
Assertion: pH of pure water is 7.
Reason: Water ionizes to give equal concentration of H⁺ and OH⁻ ions.
✅ Answer: A
9.
Assertion: The solution of a salt may be acidic, basic or neutral.
Reason: Salt is formed only by strong acids and strong bases.
✅ Answer: C
(Because salt can be formed from weak acid or base too.)
10.
Assertion: Toothpaste is basic in nature.
Reason: It neutralizes the excess acid in the mouth after eating.
✅ Answer: A
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