What finally breaks a CFC molecule apart once it reaches the stratosphere?
Environmental impacts · EPA 608 Core. The correct answer, and the reasoning behind it.
How CFCs and HCFCs destroy stratospheric ozone, and what that does to health and the environment.
The question
What finally breaks a CFC molecule apart once it reaches the stratosphere?
- Contact with water vapor in clouds
- Strong ultraviolet light from the sunCorrect answer
- Reaction with nitrogen in the air
- The cold temperatures at high altitude
Why “Strong ultraviolet light from the sun” is correct
In the stratosphere, CFCs are exposed to strong ultraviolet light that does not reach the lower atmosphere. The UV breaks the molecule and frees chlorine atoms, which then go on to destroy ozone.
Source: EPA: Test Topics
Why the other answers are wrong
- Contact with water vapor in clouds — CFCs do not dissolve or react in water vapor, which is why they survive so long.
- Reaction with nitrogen in the air — Nitrogen in the air does not break CFC molecules apart.
- The cold temperatures at high altitude — Cold alone does not split the molecule; it takes UV energy.
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