Question

A mixture of $4g$ of hydrogen and $8g$ of helium at $NTP$ has a density about

• A. $0.22kgm^{- 3}$
• B. $0.62kgm^{- 3}$
• C. $1.12kgm^{- 3}$
• D. $0.13kgm^{- 3}$

Answer 1

Answer: (D)

$4g$ $H_{2}$ means $2g$ -moles and $8g$ $He$ means $2g$ -moles.
Now $M=\frac{n_{1} M_{1} + n_{2} M_{2}}{n_{1} + n_{2}}=\frac{\left(2\right) \left(2\right) + \left(2\right) \left(4\right)}{2 + 2}$
$=3gmol^{- 1}$
$\rho =\frac{P M}{R T}=\frac{\left(1 . 013 \times \left(10\right)^{5}\right) \left(3 \times \left(10\right)^{- 3}\right)}{\left(8 . 31\right) \left(273\right)}$
$=0.13kgm^{- 3}$