Which of the following diatomic elements is represented by O2?

The diatomic element represented by O2 is oxygen. In its molecular form, oxygen exists as O2, which indicates that two oxygen atoms bond together to form a stable molecule. This diatomic nature is characteristic of many elements, particularly the nonmetals. Oxygen is essential for various biological and chemical processes, including respiration in living organisms and combustion reactions. The distinction of O2 is important because it specifically refers to the molecular form of oxygen that is abundant in Earth's atmosphere, making it critical for life.

In contrast, nitrogen is represented as N2, hydrogen as H2, and carbon is not typically found as a diatomic molecule but rather exists in various allotropes such as graphite or diamond. Thus, recognizing the specific molecular formula is essential for identifying the diatomic elements accurately.