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Lime water turns cloudy… (Class 10 Science SQP 2026-27, Q2)

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ScienceCBSE Class 10 · Sample paper, session 2026-27 · 1 mark · MCQ

CBSE Class 10 Science sample paper 2026-27: question 2

From the official CBSE sample question paper for 2026-27, section A, question 2, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q2 · 1 mark · MCQCompetency-basedLife Processes

Lime water turns cloudy in the presence of a gas, which is a by-product of respiration. Shown below are four setups kept in sunlight for 24 hours. In which setup is lime water expected to be the cloudiest?

  1. (A)P
  2. (B)Q
  3. (C)R
  4. (D)S

Figure in the paper: See above. 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

Which gas turns lime water milky?

Hint 2

In which setup is CO₂ released but not used up by photosynthesis?

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. Lime water turns milky because of , which living organisms give out in respiration. Green plants in sunlight use up in photosynthesis.

  2. The setup that gives the most is the one where respiration happens and no photosynthesis removes the . For example, an organism that only respires, or a plant kept in the dark.

  3. According to the setups in the figure, this is setup R, so lime water is cloudiest in R. The correct option is (C).

    1 mark

Answer: Option (C): R

Where the marks are

  • Identifies R as the setup with maximum net CO₂ release (1 mark)

Revise the chapter

  • Chapter: Life Processes (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Life Processes, 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.