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Chemical Reactions Class 10: Important Questions & MCQ

Check balancing, reaction types and redox with six interactive Class 10 MCQs, explained answers and five original written revision questions.

About 4 min readReviewed by Codex (AI content review)Syllabus NCERT 2026–27 reprint (selected topics)Updated 4/9/2026
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Try the six multiple-choice questions without your notes, then check the explanations. Use the written questions to practise how you would explain an answer. This is a learning check, not a prediction of the board examination. You can complete it without signing in.

Chemical reactions MCQ practice

Six-question reaction check

1. Which coefficients balance Al + O₂ → Al₂O₃, in that order?
2. Which equation represents a decomposition reaction?
3. In CuO + H₂ → Cu + H₂O, which substance is reduced?
4. Which change keeps the identity of substances intact while balancing an equation?
5. Why does an airtight container help slow rancidity?
6. What is a precipitate?

Choose one answer for each question, then check your answers.

Written important questions

  • 1. Balance P + O₂ → P₂O₅ and count atoms on both sides.
  • 2. Explain why changing a subscript is not a valid balancing step.
  • 3. Classify CaCO₃ → CaO + CO₂ on heating, and explain the energy requirement.
  • 4. Compare displacement with double displacement using one equation each.
  • 5. Explain one difference between corrosion and rancidity and a prevention method for each.

Answer guide

1–2. Conservation and formulas

  1. 14P + 5O₂ → 2P₂O₅. Both sides contain 4 phosphorus atoms and 10 oxygen atoms.
  2. 2A subscript is part of a substance’s formula. H₂O and H₂O₂ are different substances; adding a coefficient leaves the formula unchanged.

3–4. Reaction patterns

  1. 1CaCO₃ decomposes into CaO and CO₂ when heated. Energy is supplied to drive thermal decomposition.
  2. 2Displacement: Zn + CuSO₄ → ZnSO₄ + Cu; zinc replaces copper.
  3. 3Double displacement: NaCl + AgNO₃ → AgCl + NaNO₃; ions exchange partners and insoluble AgCl forms from aqueous solutions.

5. Everyday changes

  1. 1Corrosion damages metals through reactions with their surroundings; painting iron helps separate it from air and moisture.
  2. 2Rancidity is deterioration of fats and oils through oxidation; reducing oxygen exposure with suitable sealed packaging can slow it.

If you missed an atom-count question, draw a two-column tally for each element. If you missed a classification question, first count reactants and products, then look for a displaced element or exchanged ions. A reaction can fit more than one description, such as combination and exothermic.

Read the chapter notes and balancing method

Topic reference: NCERT Science, Chemical Reactions and Equations

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