Question

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

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

Answer 1

Answer: (C)

According to Boyle's law
$p_{1} V_{1}=p_{2} V_{2}$
As the pressure is decreased by $20 \%$, therefore
$P_{2}=\frac{80}{100} p_{1}$
$p_{1} V_{1}=\frac{80}{100} p_{1} V_{2}$
$V_{1}=\frac{80}{100} V_{2}$
$\therefore $ Percentage increase in volume
$=\frac{V_{2}-V_{1}}{V_{1}} \times 100$
$=\frac{100-80}{80} \times 100$
$=25 \%$