Q. The temperature of 5 moles of a gas at constant volume is changed from 100$℃$ to 120$℃$. The change in internal energy is 80 J. the total heat capacity of the gas at constant volume will be in $JK^{- 1}$ is
A) 8
B) 4
C) 0.8
D) 0.4
Explanation
(b) Number of moles $n = 5\ mol,\ \ \ T_{1} = 100℃,$
$T_{2} = 120℃,\ \ \mathrm{\Delta}U = 80\ J$
Rise in temperature $\mathrm{\Delta}t = 120 - 100 = 20℃$
$\mathrm{\Delta}U = ms\mathrm{\Delta}t$
$\frac{80}{5} = 1 \times s \times 20$
$s = 0.8\ J$
$\therefore$ For 5 mol, $s = 0.8 \times 5\ JK^{- 1} = 4\ JK^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.