Question

The number of oxygen molecules in a cylinder of volume $1\, m^ 3$ at a temperature of $27^{\circ} C$ and pressure $13.8\, Pa$ is (Boltzmaans constant $k=1.38 \times 10^{-23} J K^{-1}$ ) is :

• A. $ 6.23\times 10^{26}$
• B. $ 0.33\times 10^{28}$
• C. $ 3.3\times 10^{21}$
• D. none of these

Answer 1

Answer: (C)

Number of molecules of oxygen in the cylinder is
$n=\frac{P V}{R T}=\frac{13.8 \times 1}{1.38 \times 10^{-23} \times 300}$
$=3.3 \times 10^{21}$