Question

Question 1
Carbon exists in the atmosphere primarily in the form of:

(a) Carbon monoxide only
(b) Carbon monoxide and carbon dioxide
(c) Carbon dioxide only
(d) Methane

Answer 1

(b) Carbon monoxide and carbon dioxide.
Carbon in the atmosphere primarily exists in the form of its oxides - Carbon monoxide ($\text{CO}$) and Carbon dioxide (${\text{CO}}_2$).
Carbon monoxide is a colourless, odourless, tasteless gas which is released due to incomplete combustion of carbon.
Carbon dioxide is a colourless, acidic gas which plays a big role in controlling earth's surface temperature through the greenhouse effect. Both these gases are present in low quantities.