Question

Which two gases make the bulk of the atmosphere?

Answer 1

Two gases make up the bulk of the earth's atmosphere: nitrogen $\left(N\right)$, which comprises $78$% of the atmosphere, and oxygen $\left(O\right)$, which accounts for $21$%. Various trace gases make up the remainder. Based on temperature, the atmosphere is divided into four layers: the troposphere, stratosphere, mesosphere, and thermosphere.