Q. When two moles of oxygen is heated from $0℃ - 10℃$ at constant volume, its internal energy changes by 420 J. What is the molar specific heat of oxygen at constant volume?
A) $5.75\ JK^{- 1}mol^{- 1}$
B) $10.5\ JK^{- 1}mol^{- 1}$
C) $21\ JK^{- 1}\ mol^{- 1}$
D) $42\ JK^{- 1}mol^{- 1}$
Explanation
(c) For isochoric process, internal energy
$\mathrm{\Delta}U = nC_{V}\mathrm{\Delta}T = 420J$
Molar specific heat $C_{V} = \frac{\mathrm{\Delta}U}{n\mathrm{\Delta}T}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = \frac{420}{2 \times 10} = 21\ JK^{- 1}mol^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.