Question

In a mole of water vapour at $STP$, the volume actually occupied or taken up by the molecules (i.e., Avogadro number $\times$ the volume of one molecule) is

• A. less than $0.1 \%$ of $22.4$ litres
• B. about $10 \%$ of the volume of the container of $22.4$ litres
• C. between $10 \%$ to $20 \%$ of $22.4$ litres
• D. between $2 \%$ to $5 \%$ of $22.4$ litres.

Answer 1

Answer: (A)

One mole of water $=18\, g =18\, cm ^{3}$

(density of water $=1 \,g / cm ^{3}$ )

Volume of one mole of water vapours $=22.4 \,L =22400\, cm ^{3}$

Percentage volume actually occupied by the water molecules

$=\frac{18}{22400} \times 100=\frac{9}{112} < 0.1 \%$