Question

The number of moles of oxygen in 1 L of air containing 21% oxygen by volume in standard conditions is ____.

(A) 0.0093 mol 

(B) 0.186 mol 

(C) 0.21 mol 

(D) 2.10 mol

Answer 1

Correct option: (A) 0.0093 mol

1 L of air = 1000 mL = 1000 cc.

1000 cc of air contains 210 cc of O₂

1 mole = 22.4 L = 22400 cc.

∴ number of moles of O₂ = \(\cfrac{210}{22400}\) = 0.0093 moles.