With reference to 'ozone layer', which of the following statements is/are correct?

Question

With reference to 'ozone layer', which of the following statements is/are correct?

1. Ozone layer shields the surface of the earth from the ultra-violet radiations from the sun.

2. Ozone depletion has been linked to the chlorofluorocarbons.

Select the correct answer from the code given below:

1. A. Only 2
2. B. Neither 1 nor 2
3. C. Both 1 and 2 (Correct answer)
4. D. Only 1

Correct Answer

Option C — Both 1 and 2

Detailed Solution & Explanation

The correct answer is Both 1 and 2.

Key Points

• Statement 1 is correct. The ozone layer, in the stratosphere at about 15-35 km, absorbs most of the sun's harmful ultraviolet (UV-B and UV-C) radiation, shielding life at the surface.
• Statement 2 is correct. Ozone depletion is linked to chlorofluorocarbons (CFCs). UV light breaks CFCs, releasing chlorine atoms, and a single chlorine atom can destroy thousands of ozone molecules in a catalytic chain.
• Both hold, giving option (c).

Additional Information

• Ozone is O₃. It is "good up high, bad nearby" — protective in the stratosphere, but a pollutant and greenhouse gas in the troposphere, where it forms photochemical smog.
• The Montreal Protocol (1987) phases out ozone-depleting substances and is regarded as the most successful environmental treaty ever, with universal ratification.
• The Kigali Amendment (2016) to the Montreal Protocol phases down hydrofluorocarbons (HFCs) — these do not deplete ozone but are potent greenhouse gases.
• The Vienna Convention (1985) was the framework convention that preceded the Montreal Protocol. 16 September is observed as the International Day for the Preservation of the Ozone Layer.