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The values of a, b, c and d in… (Class 10 Science 2025, Q5)

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ScienceCBSE Class 10 · Board exam 2025, set 31/5/1 · 1 mark · MCQ

CBSE Class 10 Science 2025: question 5

Set in the CBSE Class 10 board exam of 2025, paper 31/5/1, section A, question 5, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q5 · 1 mark · MCQChemical Reactions and Equations

The values of a, b, c and d in the following balanced chemical equation are respectively:

  1. (A)1, 1, 2, 1
  2. (B)1, 1, 1, 2
  3. (C)2, 2, 1, 4
  4. (D)2, 2, 4, 1

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/5/1.

Hints

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

Hint 1

Count the N and O atoms on each side.

Hint 2

Try starting with 2 Pb(NO3)2.

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. The balanced equation is .

  2. Check: Pb = 2 on each side; N = 4 on each side; O = 12 on the left and on the right. So a, b, c, d are 2, 2, 4, 1: option (D).

    1 mark

Answer: (D) 2, 2, 4, 1

Where the marks are

  • Gives the correct coefficients (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 paper2025 board paper, set 31/5/1: 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.