Question

The relative humidity of air at any day is 50% and saturation vapour pressure at 300 $K$ is 3.6 $kPa$. The amount of water vapours per litre of air at 300 $K$ is:

• A. $26\times {10}^{-3}g$
• B. $10\times {10}^{-3}g$
• C. $13\times {10}^{-3}g$
• D. $14\times {10}^{-3}g$

Answer 1

The correct option is C $13\times {10}^{-3}g$

According to ideal gas equation:
$PV=\frac{w}{M}RT$
$3.6\times {10}^3\times {10}^{-3}\times \frac{50}{100}=\frac{w_{H_{2}O}}{18}\times 8.314\times 300$
$\therefore$ ($w$ and $M$ in $g$)
$\therefore w_{H_{2}O}=0.013g$