Question

Two flask $A$ and $B$ of equal volumes maintained at temperature $300K$ and $700K$ contains equal mass of $He\left(g\right)$ and $N_2\left(g\right)$ respectively. What is the ratio of translational kinetic energy of gas in flask $A$ to that of flask $B$ ?

• A. $1:3$
• B. $3:1$
• C. $3:49$
• D. None of these

Answer 1

The correct option is B $3:1$

$\text{Moles ratio}=\frac{n_{He}}{n_{N_2}}=\frac{\frac{w}{4}}{\frac{w}{28}}=\frac{7}{1}$
$\text{Ratio of translational K.E.=}\frac{n_{He}.T_{He}}{n_{N_2}.T_{N_2}}$
$=\frac{7}{1}\times \frac{300}{700}=3:1$