At 1 atmospheric pressure, 1.000 g of water having a volume of `1.000 cm^3` becomes 1671 `cm^3` of steam when boiled. The heat of vaporization of water at 1 atmosphere is `539 cal//g` . What is the change in internal energy during the process ?

Options

A. `204 cal`
B. `167 cal`
C. `540 cal`
D. `373 cal`

Answer

D

Explanation

`Delta Q = Delta U + Delta W`
`m=1gm`
`L_(v) = 540 cal//gm`
`Delta Q = 1 xx 540 = 540`
`540=Delta U + P Delta V`
`540=Delta U +10^(5) xx (1671-1)xx10^(-6)`
`540=DeltaU+167`
`Delta U = 540-167 = 373 cal`.