Question

Equal mass of helium and oxygen are filled in identical containers. The ratio of pressure exerted by them will be

• A. 1 : 8
• B. 1 : 16
• C. 8 : 1
• D. 16 : 11

Answer 1

The correct option is C 8 : 1

Molecular weight of Helium $M_1=4$

Molecular weight of $O_2$ $M_2=32$

Assuming their root mean square velocities to be equal, we get

$\frac{V_{rms1}}{V_{rms2}}$=$\sqrt{\frac{P_1{M}_2}{P_2{M}_1}}$ ($\because V=constatnt)$

Assuming their V${}_{rms}$ velocities to be equal

$1=\frac{P_1\left(32\right)}{P_2\left(4\right)}$

$P_2=8P_1$