Which of the following is a common human-made source of chlorine-releasing compounds that affect the ozone layer?

• A. Refrigerants
• B. Water
• C. Oxygen
• D. Nitrogen gas

Answer: (B)

Chlorine-releasing compounds released by human-made products reach the upper atmosphere and catalytically destroy ozone. Older refrigerants, like chlorofluorocarbons used in air conditioners and refrigerators, release chlorine when exposed to UV light in the stratosphere. That chlorine drives cycles that break apart ozone molecules, and one chlorine atom can destroy many ozone molecules before it’s neutralized, leading to significant ozone depletion. The other options don’t fit because water, oxygen, and nitrogen gas do not contain chlorine compounds and don’t release chlorine into the atmosphere to drive this process.