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 $22.4litres$
• D. between $2$% to $5$% of $22.4litres$

Answer 1

Answer: (A)

less than $0.1$% of $22.4$ litres

$\begin{array}{cc}1Mol\text{of water}& =18g\text{of water}\\ & =18{cm}^3\text{of water.}\end{array}$

$\therefore \text{actual volume of}1\text{mole of water}=18{cm}^3$

$\begin{array}{c}\text{Vol of}1\text{mole of water vapour at}STP=22400{cm}^3\\ \text{Percent volume actually occupied by}\\ \text{water molecules}=\frac{18\times 100}{22400}=\frac{9}{112}\end{array}$

$\Rightarrow <0.1\%$