Which gas is characterized by three oxygen atoms and is significant for Earth's atmosphere?

Ozone is characterized by its molecular structure, which consists of three oxygen atoms (O3). This triatomic formation gives ozone distinct properties that play a critical role in Earth's atmosphere. Ozone is primarily found in the stratosphere, where it forms a layer that absorbs the majority of the sun's harmful ultraviolet (UV) radiation. This absorption is vital for protecting living organisms on Earth, including humans, from the damaging effects of UV radiation, such as skin cancer and other health issues.

Ozone also contributes to the chemical balance of the atmosphere and plays a role in weather patterns and climate regulation. Its presence in the troposphere, however, can contribute to air pollution and is considered a greenhouse gas at those levels, affecting air quality and health.

The other options represent different gases with distinct structures and roles in the atmosphere: carbon dioxide consists of one carbon atom and two oxygen atoms and is a crucial greenhouse gas; nitrous oxide has two nitrogen atoms and one oxygen atom and is also a potent greenhouse gas with implications for both atmospheric chemistry and agriculture; methane is a hydrocarbon consisting of one carbon atom and four hydrogen atoms, well-known for its role as a greenhouse gas in the context of climate change.