ScienceCBSE Class 10 · Board exam 2023, set 31/2/1 · 1 mark · MCQ

CBSE Class 10 Science 2023: question 3

Set in the CBSE Class 10 board exam of 2023, paper 31/2/1, section A, question 3, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q3 · 1 mark · MCQChemical Reactions and Equations

In order to balance the following chemical equation, the values of the coefficients x and y respectively are :
$x Pb (N O_{3})_{2} Heat 2 PbO + y N O_{2} + O_{2}$

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

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/2/1.

Hints

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

Hint 1

Balance Pb first.

Hint 2

Then count the nitrogen atoms on both sides.

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.

Balancing Pb: $x = 2$ . Balancing N: $2 \times 2 = 4$ N atoms on the left, so $y = 4$ .
1 mark
Checking O: left side has $12$ ; right side has $2 + 8 + 2 = 12$ . The equation $2 Pb (N O_{3})_{2} \to 2 PbO + 4 N O_{2} + O_{2}$ is balanced.

Answer: (A) x = 2, y = 4

Where the marks are

Obtains x = 2 and y = 4 (1 mark)

Revise the chapter

Chapter: Chemical Reactions and Equations (notes, formulas, where marks are lost and every past question)
Topic: Balancing Chemical Equations

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 paper2023 board paper, set 31/2/1: every question, by section.

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CBSE Class 10 Science 2023: question 3

Hints

Step-by-step solution

Revise the chapter

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