Question

The time taken for a certain volume of gas to diffuse through a small hole was 2 min. Under similar conditions an equal volume of oxygen took 5.65 minute to pass. The molecular mass of the gas is:

• A. 32
• B. 11.33
• C. 4
• D. 8

Answer 1

Answer: (C)

4

We know that
$\frac{r_1}{r_2}=\sqrt{\frac{M_1}{M_1}}=\frac{v_{1+2}}{v_{2+1}}$ $v_1=v_2$
$\sqrt{\frac{32}{M}}=\frac{v_1\times 5.65}{v_1\times 2}$
$\frac{32}{M}=(2.825{)}^2=7.98$
$M=\frac{32}{7.98}=4.0$