Question

Children brought some balloons each of 2 litre capacity to a chemist and asked him to fill them with hydrogen gas. The chemist possessed 8 litre cylinder containing hydrogen at 10 atm pressure at room temperature. How many balloons could he fill with hydrogen gas at normal atmospheric pressure at the same temperature?

• A. $40$
• B. $36$
• C. $32$
• D. $28$

Answer 1

Answer: (A)

$40$

Initial pressure in the cylinder $P$ $=$ 10 atm.
Initial volume in the cylinder $V$ $=$ 8 L.
Final pressure in the balloons $P^{\prime }$ $=$ 1 atm.
Final volume in the balloons $V^{\prime }$ $=$ ??
$PV=P^{\prime }{V}^{\prime }$ at same temperature
$\text{10 atm}\times \text{8 L}=\text{1 atm}\times V^{\prime }$
$V^{\prime }=\text{80 L}$
The number of balloons ( each of 2 litre capacity ) that he could fill $=\frac{\text{80 L}}{\text{2 L}}=40$