Skip to content

A gas 'X' which is a deadly… (Class 10 Science 2024, Q33B)

questionbuddy.in/q/cbse-10-science-2024-31-1-1-q33b-gas-deadly-poison-found-higher

ScienceCBSE Class 10 · Board exam 2024, set 31/1/1 · 3 marks · Short answer

CBSE Class 10 Science 2024: question 33(B)

Set in the CBSE Class 10 board exam of 2024, paper 31/1/1, section C, question 33(B), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q33(B) · 3 marks · Short answerOur Environment

A gas 'X' which is a deadly poison is found at the higher levels of atmosphere and performs an essential function.
Name the gas and write the function performed by this gas in the atmosphere. Which chemical is linked to the decrease in the level of this gas? What measures have been taken by an international organization to check the depletion of the layer containing this gas?

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/1/1.

Hints

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

Hint 1

The gas is a form of oxygen with three atoms.

Hint 2

Which synthetic chemicals from refrigerators harm this layer, and what did UNEP decide in 1987?

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. Gas X is **ozone ()**.

    1 mark

  2. Function: the ozone layer shields the Earth's surface from harmful ultraviolet (UV) radiation from the Sun.

    1 mark

  3. Chemical linked to its depletion: chlorofluorocarbons (CFCs), used in refrigerants and fire extinguishers.

    ½ mark

  4. Measure: in 1987 UNEP brought about an agreement to freeze CFC production at 1986 levels. CFC-free refrigerators are now made.

    ½ mark

Answer: Ozone; absorbs/shields UV radiation; CFCs; UNEP agreement to freeze CFC production at 1986 levels

Where the marks are

  • Names ozone (1 mark)
  • Protects from UV radiation (1 mark)
  • Names CFCs (½ mark)
  • UNEP agreement to freeze CFC production at 1986 levels (½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Our Environment, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 31/1/1: 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.