Question

An open vessel containing air is heated from 300 K to 400 K. 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

Answer: (B)

1/4

According to ideal gas equation

$PV=nRT$

$\Rightarrow n\propto \frac{1}{T}$

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

Given that:-

$n_1=1$

$T_1=300K$,

$T_2=400K$

$n_2=?$

$\therefore \frac{1}{n_2}=\frac{400}{300}$

$n_2=\frac{3}{4}$

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

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