Ozone in the Earth's stratosphere is created by UV light striking which molecule?

Ozone in the Earth's stratosphere is created when ultraviolet (UV) light strikes oxygen molecules. Specifically, UV light causes the oxygen molecules (O₂) to dissociate into individual oxygen atoms (O). These free oxygen atoms can then react with other oxygen molecules to form ozone (O₃). This process is crucial for the ozone layer, which serves to absorb and block a significant amount of harmful UV radiation from reaching the Earth's surface.

The other options, such as nitrogen, hydrogen, and carbon dioxide, do not play a direct role in the formation of ozone in the stratosphere. While nitrogen is abundant in the atmosphere, it does not directly contribute to ozone formation through UV interaction. Hydrogen and carbon dioxide also do not have the same chemical reactions that lead to ozone production under UV light. Thus, oxygen is the key molecule involved in the generation of ozone, solidifying its importance in the process.