Log inStart free

The ozone layer and how it is being depleted

Usually 2 marks a paper · mostly short answers and assertion-reason · asked in 2 of the last papers

Notes are being written

The board questions below are real and complete — they come from the CBSE papers themselves. The written notes for this topic are still being prepared.

Board questions on this topic

3 from the CBSE papers we hold — the exact wording the board used.

2025Assertion-Reason·1 mark·Q20

Assertion (A): The amount of ozone in the atmosphere began to drop sharply in the 1980s. Reason (R): The oxygen atoms combine with molecular oxygen to form ozone. Select the correct answer:

  1. (a) Both A and R are true and R is the correct explanation of A.
  2. (b) Both A and R are true, but R is not the correct explanation of A.
  3. (c) A is true, but R is false.
  4. (d) A is false, but R is true.

2024Short answer·3 marks·Q33(b)

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?

2022Very short answer·2 marks·Q7(a)

What is ozone? How is it formed in the upper layers of the Earth's atmosphere? How does ozone affect our ecosystem?