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A. A soda bottle… (Class 12 Chemistry SQP 2024-25, Q17b)

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ChemistryCBSE Class 12 · Sample paper, session 2024-25 · 2 marks · Very short answer

CBSE Class 12 Chemistry sample paper 2024-25: question 17(b)

From the official CBSE sample question paper for 2024-25, section B, question 17(b), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q17(b) · 2 marks · Very short answerCompetency-basedChemistry in Everyday Life

a. A soda bottle will go flat (loose its fizz) faster in Srinagar than in Delhi. Is this statement correct? Why or why not? (1)
b. How does sugar help in increasing the shelf life of the product? (1)

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2024-25.

Hints

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

Hint 1

How does atmospheric pressure change with altitude?

Hint 2

Which law links the solubility of a gas to its pressure?

Hint 3

For (b), think of which way water moves across a bacterial cell membrane in a strong sugar solution.

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) Yes, the statement is correct. Srinagar is at a high altitude, so atmospheric pressure (and the partial pressure of above the opened drink) is lower than in Delhi.

    ½ mark

  2. By Henry's law, the solubility of a gas is directly proportional to its partial pressure above the solution. Less stays dissolved at lower pressure, so the gas escapes faster and the soda goes flat sooner in Srinagar.

    ½ mark

  3. (b) A high concentration of sugar makes the surroundings hypertonic to any microbe on the food.

    ½ mark

  4. By osmosis, water moves out of the bacterial or fungal cells. They shrink (plasmolyse) and die, so the product does not spoil and its shelf life increases.

    ½ mark

Answer: (a) Correct: lower pressure at Srinagar means lower CO₂ solubility (Henry's law); (b) sugar draws water out of microbes by osmosis, killing them

Where the marks are

  • States the statement is correct and pressure is lower at high altitude (½ mark)
  • Applies Henry's law: less CO₂ dissolved, so the drink goes flat faster (½ mark)
  • Sugar solution is hypertonic to microbes (½ mark)
  • Water leaves microbial cells by osmosis and they shrivel and die (½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Chemistry in Everyday Life, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2024-25: 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.