Question

An open vessel containing air is heated from ${27}^{o}C$ to ${127}^{o}C$. The fraction of air originally present which goes out of it is:

• A. $3/4$
• B. $1/4$
• C. $2/3$
• D. $1/8$

Answer 1

The correct option is B $1/4$

$PV=nRT$

Given,

$n_1=1$

$T_1=300K$

$T_2=400K$

Also,

$P_1{V}_1=n_{1}R{T}_1$

$P_2{V}_2=n_{2}RT$

$\frac{n_1}{n_2}=\frac{T_2}{T_1}$

$⟹n_2=\frac{3}{4}$

The fraction of air present in vessel after heating $n_2=\frac{3}{4}$

The fraction of air which goes out of the vessel $=1-\frac{3}{4}=\frac{1}{4}$

Hence,option B is correct answer