Question

Which compound is mainly responsible for the depletion of ozone layer?

• A. \(CO_2\)
• B. \(CH_4\)
• C. \(CH_3OH\)
• D. \(CF_2Cl_2\)

Hint:

Remember the distinction:
- Greenhouse Effect (Global Warming) \(\rightarrow\) CO\(_2\), CH\(_4\).
- Ozone Depletion \(\rightarrow\) CFCs (compounds with Chlorine and Fluorine).

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
We need to identify the compound from the list that is the primary cause of the destruction of the stratospheric ozone layer.

Step 2: Key Formula or Approach:
Ozone layer depletion is primarily caused by chemical compounds containing chlorine and bromine that are stable enough to reach the stratosphere, known as chlorofluorocarbons (CFCs).

Step 3: Detailed Explanation:
The stratospheric ozone layer is depleted by catalytic reactions involving free radicals, primarily chlorine (\(Cl\cdot\)) and bromine (\(Br\cdot\)) radicals.
The main source of these halogen radicals is a class of man-made compounds called

Chlorofluorocarbons (CFCs).
Let's look at the options:
-

(A) \(CO_2\): A greenhouse gas, but does not deplete ozone.
-

(B) \(CH_4\): A greenhouse gas, but does not directly deplete ozone.
-

(C) \(CH_3OH\) (Methanol): Decomposes in the lower atmosphere and does not significantly affect the ozone layer.
-

(D) \(CF_2Cl_2\) (Dichlorodifluoromethane): This is a classic example of a CFC (Freon-12). In the stratosphere, UV radiation breaks its C-Cl bonds, releasing chlorine free radicals that catalytically destroy ozone.

Step 4: Final Answer:
The compound mainly responsible for the depletion of the ozone layer is \(CF_2Cl_2\).