TeXes Science Practice Test

During the early formation of the Earth, what contributed to the breakdown of ammonia and methane in the atmosphere?

1. Volcanic eruptions

2. Earthquakes

3. The sun's ultraviolet radiation

4. Ocean waves

The correct answer is: The sun's ultraviolet radiation

The breakdown of ammonia and methane in the early Earth's atmosphere was significantly influenced by the sun's ultraviolet radiation. In the primordial environment, these gases were prevalent, but the intense ultraviolet light from the young sun provided enough energy to initiate chemical reactions that decomposed them into simpler molecules. This process is known as photolysis, where high-energy photons from sunlight break chemical bonds. The other factors listed, such as volcanic eruptions, earthquakes, and ocean waves, certainly played important roles in shaping the early Earth and contributing to its atmosphere and geology. However, they do not have the same direct impact on the chemical breakdown of ammonia and methane through ultraviolet radiation. Volcanic eruptions could release gases and contribute to atmospheric composition, while earthquakes and ocean waves affect land and water dynamics, but they do not specifically account for the decomposition of these gases resulting from a photochemical process. Thus, the sun's ultraviolet radiation is key to understanding this aspect of early atmospheric chemistry.