Thermodynamics Question 179
Question: Unit mass of a liquid with volume $ V _{1} $ is completely changed into a gas of volume $ V _{2} $ at a constant external pressure P and temperature T. If the latent heat of evaporation for the given mass is L, then the increase in the internal energy of the system is
[Roorkee 1999]
Options:
A) Zero
B) $ P(V _{2}-V _{1}) $
C) $ L-P(V _{2}-V _{1}) $
D) L
Show Answer
Answer:
Correct Answer: C
Solution:
$ \Delta Q=\Delta V+P\Delta V $
Therefore mL = DU + P(V2 - V1)
Therefore DU = L - P (V2 - V1) ($ \because $ m = 1)
