Question

If the pressure of a gas contained in a vessel is increased by $0.4\%$ when heated through $1^{\circ}C$, the initial temperature had been :

• A. $2500 \,K$
• B. $250 \,K$
• C. $250^{\circ} C$
• D. $25^{\circ} C$

Answer 1

Answer: (C)

$250^{\circ} C$

Answer 2

According to Charles law $\frac{d P}{P}=\frac{d T}{T}$ Here: $d T=1^{\circ} C \,dP$ is change in pressures $=0.4 \%$ $\frac{d P}{P}=\frac{0.4}{100}$ or $\frac{0.4}{100}=\frac{1}{T}$ So, $T=\frac{100}{0.4}=250^{\circ} C$