Class 10 Science Chapter 1: Chemical Reactions and Equations — practice questions with answers
Free practice for Class 10 Science, Chapter 1: Chemical Reactions and Equations. Try the solved questions below, then take a free test with instant marking and explanations.
49 questions22 easy, 20 medium, 7 hardNCERT · CBSE · State boards
Sample questions with solutions
Q1. When a magnesium ribbon is burnt in air, the white powder formed is ______.
- magnesium oxide
- magnesium hydroxide
- magnesium carbonate
- magnesium nitride only
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Answer: A. magnesium oxide
Why: 2Mg + O₂ → 2MgO; it burns with a dazzling white flame. [p.1]
Why: 2Mg + O₂ → 2MgO; it burns with a dazzling white flame. [p.1]
Q2. Which law requires a chemical equation to be balanced?
- Law of conservation of mass
- Law of constant proportions
- Ohm's law
- Law of reflection
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Answer: A. Law of conservation of mass
Why: Mass can neither be created nor destroyed in a chemical reaction. [p.3]
Why: Mass can neither be created nor destroyed in a chemical reaction. [p.3]
Q3. An unbalanced chemical equation is also called a ______ chemical equation.
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Answer: skeletal
Why: Fe + H₂O → Fe₃O₄ + H₂ is a skeletal equation until balanced. [p.3]
Why: Fe + H₂O → Fe₃O₄ + H₂ is a skeletal equation until balanced. [p.3]
Q4. The symbol (aq) written after a formula in an equation means the substance is ______.
- present as a solution in water
- a gas
- a solid
- a liquid acid
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Answer: A. present as a solution in water
Why: (s), (l), (g) and (aq) show physical states. [p.5]
Why: (s), (l), (g) and (aq) show physical states. [p.5]
Q5. Reactions in which heat is released along with the products are called ______ reactions.
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Answer: exothermic
Why: Burning of natural gas and respiration are exothermic. [p.7]
Why: Burning of natural gas and respiration are exothermic. [p.7]
Q6. The slow eating away of a metal such as iron by moisture, air and acids is called ______.
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Answer: corrosion
Why: Rusting of iron is corrosion. [p.13]
Why: Rusting of iron is corrosion. [p.13]
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Frequently asked questions
How many practice questions are there for Class 10 Science Chapter 1: Chemical Reactions and Equations?
49 questions (22 easy, 20 medium, 7 hard). A few are solved on this page; the free test shows the answer and explanation for every question after you submit.
Is this chapter from the NCERT book?
Yes — it follows the NCERT Class 10 Science syllabus, used by CBSE and many state boards.