The gas that is less dense than air is

A.

nitrogen

B.

chlorine

C.

Carbon(IV) oxide

D.

Oxygen

Correct answer is A

The density of a gas is directly proportional to its molar mass. This means that gases with a lower molar mass will be less dense than gases with a higher molar mass. Nitrogen (N2) has a molar mass of 28 g/mol, which is less than that of air (approximately 29 g/mol), making it less dense than air.