Q. Calculate change in internal energy when 5 mole of hydrogen is heated to $20℃$ from $10℃$, specific heat of hydrogen at constant pressure is 8 cal $(mol{^\circ}C)^{- 1}$
A) 200 cal
B) 350 cal
C) 300 cal
D) 475 cal
Explanation
(c) $C_{p} = 8$ cal $(mol℃)^{- 1},\ C_{v} = C_{p} - R = 8 - 2 = 6$ cal $(mol\ ℃)^{- 1}$
$dU = mC_{v}\left( T_{2} - T_{1} \right) = 5 \times 6(20 - 10) = 300\ cal$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.