Chlorofluorocarbons may be harming the ozone layer by ____.

• A. releasing chlorine atoms that catalyze the breakdown of ozone molecules
• B. absorbing ultraviolet radiation and preventing ozone formation
• C. directly reacting with oxygen to form carbon dioxide
• D. increasing the concentration of greenhouse gases in the atmosphere

Answer: (A)

Verified step by step guidance

1. Understand the role of chlorofluorocarbons (CFCs) in the atmosphere: CFCs are stable compounds that can reach the stratosphere without breaking down easily.
2. Recognize that in the stratosphere, ultraviolet (UV) radiation breaks down CFC molecules, releasing chlorine atoms (Cl·).
3. Know that these chlorine atoms act as catalysts in the breakdown of ozone (O\_3) molecules by reacting with ozone to form chlorine monoxide (ClO·) and oxygen (O\_2).
4. Understand the catalytic cycle: chlorine monoxide can react with a free oxygen atom to regenerate the chlorine atom and produce more oxygen, allowing one chlorine atom to destroy many ozone molecules.
5. Conclude that the primary harm caused by CFCs to the ozone layer is due to the release of chlorine atoms that catalyze the breakdown of ozone molecules, reducing the ozone concentration.