Q. Which of the following are considered Ozone Depleting Substances (ODS)?

1. Halons
2. Methyl bromide
3. Carbon tetrachloride
4. Methyl chloroform

Select the correct option using the codes given below:
Answer: 1, 2, 3 & 4
Notes: Halons, methyl bromide, carbon tetrachloride, and methyl chloroform are all classified as ozone depleting substances under the Montreal Protocol. These chemicals contribute to the breakdown of ozone in the stratosphere, leading to ozone layer depletion. Chlorofluorocarbons, halons, carbon tetrachloride, methyl chloroform, and methyl bromide are the main ODS regulated globally.