How are individual atoms of oxygen (O) formed in the stratosphere?

• A. By the photodissociation of molecular oxygen (O_2) by ultraviolet light
• B. By the combination of ozone (O_3) with nitrogen dioxide (NO_2)
• C. By the reaction of carbon dioxide (CO_2) with sunlight
• D. By the condensation of water vapor

Answer: (A)

Verified step by step guidance

1. Understand that the question asks about the formation of individual oxygen atoms (O) in the stratosphere, which involves breaking down molecules to produce atomic oxygen.
2. Recall that molecular oxygen (O_2) can absorb ultraviolet (UV) light in the stratosphere, causing it to split into two individual oxygen atoms. This process is called photodissociation.
3. Write the photodissociation reaction: \(\mathrm{O_2} + h\nu \rightarrow 2\mathrm{O}\), where \(h\nu\) represents the energy of UV light.
4. Recognize that other options, such as reactions involving ozone (O_3) with nitrogen dioxide (NO_2), carbon dioxide (CO_2) with sunlight, or condensation of water vapor, do not produce atomic oxygen directly.
5. Conclude that the formation of individual oxygen atoms in the stratosphere primarily occurs through the photodissociation of molecular oxygen by ultraviolet light.