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Consider a system in… (Class 12 Chemistry SQP 2026-27, Q5)

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ChemistryCBSE Class 12 · Sample paper, session 2026-27 · 1 mark · MCQ

CBSE Class 12 Chemistry sample paper 2026-27: question 5

From the official CBSE sample question paper for 2026-27, section A, question 5, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q5 · 1 mark · MCQCompetency-basedSolutions

Consider a system in a state of dynamic equilibrium, as shown in Fig. 1(a). The lower part is solution and the upper part is gaseous system at pressure p and temperature T. If the pressure is increased over the solution phase by compressing the gas to a smaller volume as shown in Fig 1(b).

Which of the following statements is true about figure 1(b)

  1. (A)solubility of gas will increase until dynamic equilibrium is reached
  2. (B)solubility of gas will decrease until dynamic equilibrium is reached
  3. (C)solubility of gas will increase until static equilibrium is reached
  4. (D)solubility of gas will decrease until static equilibrium is reached

Figure in the paper: Figure 1: (a) a container with solution below and gas above, closed by a piston carrying one weight W1; (b) same container with the piston carrying three weights (W1, W2, W3), gas compressed to smaller volume, more gas particles shown dissolved in the solution. See it in the official paper.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

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

Hint 1

Recall which law links gas pressure to gas solubility.

Hint 2

Think about whether molecular exchange stops at equilibrium.

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. By Henry's law, the solubility of a gas is proportional to its partial pressure. Compressing the gas raises the pressure, so more gas dissolves.

    1 mark

  2. Dissolution and escape of gas molecules continue at equal rates once the new state is reached, so the equilibrium is dynamic, not static.

Answer: Option (A)

Where the marks are

  • Applies Henry's law: solubility increases until dynamic equilibrium is re-established (1 mark)

Revise the chapter

  • Chapter: Solutions (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Solutions, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2026-27: 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.