<Dl> <Dd> CO → CO + (O) (atomic oxygen) </Dd> <Dd> CH + 2 (O) → CH O + H O </Dd> <Dd> CO + NH → HCN + H O </Dd> <Dd> CH + NH → HCN + 3H (BMA process) </Dd> </Dl> <Dd> CO → CO + (O) (atomic oxygen) </Dd> <Dd> CH + 2 (O) → CH O + H O </Dd> <Dd> CO + NH → HCN + H O </Dd>

What gas that is important for life today was not present in the early atmosphere