Question

A weather balloon filled with hydrogen at $1\text{atm}$ and $300\text{K}$ has a volume equal to 12000 litres. On ascending it reaches a place where temperature is $250\text{K}$ and pressure is $0.5\text{atm}$. The volume of the balloon is:

• A. 24000 litres
• B. 20000 litres
• C. 10000 litres
• D. 12000 litres

Answer 1

The correct option is B 20000 litres

Let $P_1{V}_1$ and $T_1$ be the initial pressure-volume and temperature respectively . and $P_2,V_2$ and $T_2$ be the final pressure-volume and temperature respectively. The number of moles are the same.

Using $\frac{P_1{V}_1}{T_1}=\frac{P_2{V}_2}{T_2};\frac{1\text{atm}\times 12000\text{L}}{300\text{K}}=\frac{0.5\text{atm}\times V_2}{250\text{K}}$
$\therefore V_2=20,000\text{L}$