What is the apparent molecular weight of air assuming it contains 78% of N2, 21% of O2 and 1% argon by volume

Answer 1

78% N2 x 28.01 g N2/mol = 21.85 g N2

21% O2 x 32 g O2/mol = 6.72 g O2

1% Ar x 39.95 g Ar/mol = 0.3995 g Ar

Total mass = 21.85 g + 6.72 g + 0.3995 g = 28.97 g

Apparent molar mass = 28.97 g/mole