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Which of the following are… (Class 10 Science 2026, Q17)

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ScienceCBSE Class 10 · Board exam 2026, set 31/2/1 · 1 mark · MCQ

CBSE Class 10 Science 2026: question 17

Set in the CBSE Class 10 board exam of 2026, paper 31/2/1, section B, question 17, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q17 · 1 mark · MCQChemical Reactions and Equations

Which of the following are combination reactions ?

(i)
(ii)
(iii)
(iv)

  1. (A)(i) and (iii)
  2. (B)(iii) and (iv)
  3. (C)(ii) and (iv)
  4. (D)(ii) and (iii)

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/2/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Count the products in each reaction.

Hint 2

A combination reaction has only one product.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. A combination reaction joins two or more reactants into a single product.

  2. (ii) MgO + H₂O → Mg(OH)₂ and (iii) 4Al + 3O₂ → 2Al₂O₃ each give a single product. Reaction (i) is decomposition and (iv) is displacement. Option (D).

    1 mark

Answer: (ii) and (iii), option (D)

Where the marks are

  • Identifies (ii) and (iii) as combination reactions (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Chemical Reactions and Equations, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 31/2/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.