Question

It is found that with an increase in temperature by 40% the volume decreases by 20% with change in pressure. Find the percentage change in pressure.

• A. 40% decrease
• B. 60% decrease
• C. 75% increase
• D. 80% increase

Answer 1

Answer: (C)

75% increase

If initial temperature is $T$, final temperature is $T+\frac{40}{100}\times T=1.4T$

If initial volume is $V$, final volume is $V-\frac{20}{100}\times V=0.8V$

Applying the gas equation, we get $\frac{P_1{V}_1}{T_1}=\frac{P_2{V}_2}{T_2}$

If initial pressure is $P$, final pressure $=\frac{1.4T\times V\times P}{0.8V\times T}=1.75P$

$\therefore$ Increase in pressure $=1.75-1=0.75$

Percentage increase $=0.75\times 100=75\%$

Hence, option C is correct.