The thinning of the ozone umbrella is due to:
- 1. PAN
- 2. Freons
- 3. CO₂
- 4. NO
- A2 and 4 are correct
- BBoth 2 and 3 are correct
- C1 and 4 are correct
- D1, 3 and 4 are correct
Show answer and explanation
Correct answer: (a) 2 and 4 are correct
Explanation
The ozone layer in the stratosphere is thinned by:
- freons (chlorofluorocarbons, CFCs): ultraviolet light breaks them and releases chlorine atoms, and each chlorine atom can destroy thousands of ozone molecules;
- nitric oxide (NO): from supersonic aircraft and other sources, it destroys ozone in chain reactions.
PAN (peroxyacetyl nitrate) is a pollutant of photochemical smog near the ground, and carbon dioxide is a greenhouse gas. Neither destroys stratospheric ozone.