Q. The following sets of values for $C_{V}$ and $C_{P}$ of a gas has been reported by different students. The units are $cal/g$-$mole$-$K.$ Which of these sets is most reliable
A) $C_{V} = 3,\ C_{P} = 5$
B) $C_{V} = 4,\ C_{P} = 6$
C) $C_{V} = 3,\ C_{P} = 2$
D) $C_{V} = 3,\ C_{P} = 4.2$
Explanation
(a) $C_{P} - C_{V} = R = 2.\frac{cal}{g - mol - K}$
Which is correct for option (a) and (b). Further the ratio $\frac{C_{P}}{C_{V}}( = \gamma)$ should be equal to some standard value corresponding to that of either, mono, di, or triatomic gases. From this point of view option (a) is correct because $\left( \frac{C_{P}}{C_{V}} \right)_{mono} = \frac{5}{3}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.