Question

At constant pressure, a sample of helium gas has a volume of 800 ml at ${27}^{o}C$. Calculate the temperature at which the volume will become 20% of its initial volume.

• A. 20 K
• B. ${60}^{o}C$
• C. 150 K
• D. $-{213}^{o}C$

Answer 1

The correct option is D $-{213}^{o}C$

$V=800ml;T={27}^{o}C=27+273=300K$

$V_1=0.2V=0.2\times 800=160ml$

$\frac{V}{V_1}=\frac{T}{T_1}$

$\frac{800}{160}=\frac{300}{T_1}$

$T_1=\frac{300\times 160}{800}=3\times 20=60K$

$C=K-273$

$C=60-273$ $=-{213}^{o}C$