Q 41

Ten kilograms of water at 0C is mixed with 10 kg of water at 100C.The change in entropy (in cal/K)of the system is
A)1 000
B)480
C)720
D)240
E)168

Q 42

A vessel containing 10 kg of water is left out where it evaporates.If the temperature remains constant at 20C,what is the change in entropy (in kcal/K)? (The latent heat of vaporization at 20C is 585 cal/g. )
A)30
B)10
C)20
D)40
E)290

Q 43

A gasoline engine absorbs 2 500 J of heat at 250C and expels 2 000 J at a temperature of 50C.The magnitude of the change in entropy (in J/K)for the system is
A)6.2
B)4.7
C)1.4
D)10.9
E)3.2