Question

A cylinder with fixed capacity of $67.2$ lit contains helium gas at STP. The amount of heat needed to raise the temperature of the gas by ${20}^{0}C$ is :

• A. $748J$
• B. $374J$
• C. $350J$`
• D. $700J$

Answer 1

Answer: (A)

$748J$

$\Delta Q=n{C}_V\Delta T=n\frac{3}{2}R\Delta T$
$=\left(\frac{67.2}{22.4}\right)\times (\frac{3}{2}\times 8.31)\times \left(20\right)$
$\approx 748J$