Which catalyzed reaction is responsible for breaking up ozone in the stratosphere?

• A. Cl + O3 → ClO + O2
• B. SO2 + O3 → SO3 + O2
• C. NO2 + O3 → NO3 + O2
• D. CO + O3 → CO2 + O2

Answer: (A)

Verified step by step guidance

1. Understand that the question asks which catalyzed reaction is responsible for breaking up ozone (O\_3) in the stratosphere, focusing on reactions involving radicals or species that can catalytically destroy ozone molecules.
2. Recall that chlorine radicals (Cl) are well-known catalysts in ozone depletion because they react with ozone to form chlorine monoxide (ClO) and oxygen (O\_2), and then regenerate the Cl radical to continue the cycle.
3. Examine the given reactions and identify which involves a radical species known for catalyzing ozone destruction. The reaction Cl + O\_3 → ClO + O\_2 fits this description because Cl is a radical that initiates ozone breakdown.
4. Recognize that other reactions listed (involving SO\_2, NO\_2, CO) do not represent catalytic cycles that break down ozone in the stratosphere; they are either not radical-driven or not significant in ozone depletion chemistry.
5. Conclude that the catalyzed reaction responsible for breaking up ozone in the stratosphere is the one involving chlorine radicals: Cl + O\_3 → ClO + O\_2.