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CDoubt No 000001 - JEE


Question : An evacuated vessel weighs $50g$ when empty, $144g$ when filled with liquid of density $0.47 g/ml$ and $50.5 g$ when filled with an ideal gas at $760\text{ mm Hg }$ at $300K$. The molar mass of the ideal gas is (Given $R=0.0821\text{ L atm }K^{-1}mol^{-1}$)

(a) $61.575$
(b) $130.98$
(c) $123.75$
(d) $47.87$

Solution : Weight of fluid $=144-50=94 g$
Density of liquid $=0.47 g/ml$
So, Volume of liquid $=\dfrac{94}{0.47}=200 ml=0.2 L$
Weight of glass $=50.5-50=0.5 g$
Now $PV=nRT$
$\implies 1\times0.2=\dfrac{0.5}{M}\times 0.0821\times 300$
$\implies M=61.575$
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