Kinetic Theory Ques 2
2. A cylinder contains hydrogen gas at pressure of $249 $ $kPa$ and temperature $27^{\circ} C$. Its density is : $(R=8.3 $ $J $ $mol^{-1} K^{-1})$
[2020]
(a) $0.2 $ $kg / m^{3}$
(b) $0.1 $ $kg / m^{3}$
(c) $0.02 $ $kg / m^{3}$
(d) $0.5 $ $kg / m^{3}$
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Answer:
Correct Answer: 2.(a)
Solution:
- (a) Given : Pressure $P=249$ $ kPa$
$ =249 \times 10^{3}$ $ N / m^{2} $
Mass of hydrogen, $M=2 g=2 \times 10^{-3} $ $kg$
Temperature, $T=27+273=300 $ $K$
Using, ideal gas equation, $P V=n R T$
$ P M=\rho R T \Rightarrow \rho=\frac{P M}{R T} \quad(\because \rho=\frac{M}{V}) $
$\therefore \rho=\frac{(249 \times 10^{3})(2 \times 10^{-3})}{8.3 \times 300}=0.2 $ $kg / m^{3}$.
BETA
