Methane gas is heavier or lighter than air and is it a kitchen gas?

According to Avogadro’s law, one mole of any gas occupies the same volume, and it contains the same number of molecules.
With an equal number of molecules in the same volume, to compare the density of gases, it is enough to compare the masses of individual molecules that make up its composition.
In atomic mass unit, a methane molecule (one carbon atom and four hydrogen atoms): Mm = 12 + 4 = 16 amu. eat.
Air consists mainly of oxygen (two atoms) and nitrogen (two atoms) molecules:
Mk = 16 * 2 = 32 amu. eat.
Ma = 14 * 2 = 28 amu. eat.
Methane is lighter than oxygen and nitrogen, therefore it is lighter than air.
Kitchen gas is a mixture of gases that includes methane (70% to 98%).
Answer: methane is lighter than air.