States of Matter - Result Question 6
####6. $\quad 50 mL$ of each gas $A$ and of gas $B$ takes 150 and 200 seconds respectively for effusing through a pin hole under the similar condition. If molecular mass of gas $B$ is 36 , the molecular mass of gas $A$ will be :
[2012]
(a) 96
(b) 128
(c) 32
(d) 64
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Solution:
- (N) $\frac{V_A}{t_A} / \frac{V_B}{t_B}=\sqrt{\frac{M_B}{M_A}}$
$\frac{t_B}{t_A} \Rightarrow \frac{200}{150}=\sqrt{\frac{36}{M_A}} \Rightarrow \frac{4}{3}=\sqrt{\frac{36}{M_A}}$
$\Rightarrow \frac{16}{9}=\frac{36}{M_A} \Rightarrow M_A=\frac{81}{4}=20.25$
