Question

The density of air is 0.001293 g/ml at STP. Its vapour density will be:

• A. 10
• B. 15
• C. 1.44
• D. 14.4

Answer 1

Answer: (D)

14.4

Given density$=0.001293$ g/ml

1 ml contains $0.001293$ g, thus $22400$ ml will contain $0.001293\times 22400=28.96$ g.

Hence, molecular weight of air$=28.96$ g

$\therefore$ vapour density $=\frac{\text{molecular mass}}{2}\approx 14.4$ g