Question

Temperature remaining constant, the pressure of a gas is decreased by 20%. The percentage change in volume is

• A. increases by $20$%
• B. decreases by $20$%
• C. increases by $25$%
• D. decreases by $25$%

Answer 1

The correct option is C increases by $25$%

Ideal gas equation states that: $PV=nRT$

As temperature remains constant, so PV$=$ constant $=$k

As pressure decreases by $20\%$ so $P_2=0.8$P

$\Rightarrow PV=\left(0.8P\right)V_2$

$\Rightarrow V_2=\frac{PV}{0.8P}=\frac{V}{0.8}=1.25V$

So volume of gas increases by $25\%$.