Indicate whether the following statements are true or false for a reversible isothermal process: (A) Q=T (∆S). (B) ∆U=0. (C) The entropy change of the system is always zero. (D) The total entropy change of the system and the surroundings is zero. (E) Q=W. (F) The entropy change of the environment is negative. (G) The total entropy change of the system and the surroundings is negative.

A) True

B) True

C) False

D) True

E) True

F) False

G) False

Explanation:

Reversible - isothermal process:

We know that a process called reversible if when this process will be revers then it will not leave any effect on surrounding will return in original state.

A process is called isothermal process if, initial and final temperature is same.

A)

Q=TΔS

Yes it is true for reversible and isothermal process.

B)

ΔU = 0

For isothermal process ΔU = 0.

It is true only for ideal gas.

C) The entropy change of system can be positive, negative.

So it is false.

D)

We know that

Entropy change of universe = Entropy change of system + Entropy change of surrounding.

For reversible process

Entropy change of universe = 0

So it is true.

E)

From first law

Q = ΔU + W

For isothermal process ΔU = 0. (only for ideal gas)

⇒Q = W

So it is true.

F)

The entropy change of surrounding can be positive, negative.

So it is false.

G) We know that total entropy change of universe given as

Entropy change of universe = Entropy change of system + Entropy change of surrounding.

For reversible process

Total Entropy change of universe = 0

So it is false.