Consider the following processes: I. Energy flows as heat....

[Any Help]

Homework Statement

Consider the following processes: I. Energy flows as heat from a hot object to a colder object II. Work is done on a system and an equivalent amount of energy is rejected as heat by the system III. Energy is absorbed as heat by a system and an equivalent amount of work is done by the system .Which are never found to occur?
A. Only I
B. Only II
C. Only III
D. Only II and III
E. I, II, and III
ans: C

Homework Equations

The Attempt at a Solution

Why its C??

 

[Chestermiller]

Homework Statement

Consider the following processes: I. Energy flows as heat from a hot object to a colder object II. Work is done on a system and an equivalent amount of energy is rejected as heat by the system III. Energy is absorbed as heat by a system and an equivalent amount of work is done by the system .Which are never found to occur?
A. Only I
B. Only II
C. Only III
D. Only II and III
E. I, II, and III
ans: C

Homework Equations

The Attempt at a Solution

Why its C??

It is wrong. That's why.

 

[Any Help]

It is wrong. That's why.

I mean why it is wrong?

 

[Chestermiller]

I mean why it is wrong?

This is the same thing as an isothermal expansion, which you can always do. What they erroneously neglected to consider is this can never be done for a system operating in a cycle using a single (isothermal) reservoir.

 

[vela]

I mean why it is wrong?

It looks like whoever wrote the question is using the word system to mean heat engine. Try calculating the efficiency of the described engine.

 

[Chestermiller]

It looks like whoever wrote the question is using the word system to mean heat engine. Try calculating the efficiency of the described engine.

Another requirement is that there be only one reservoir to supply heat (and no reservoir to remove heat). This is basically the Kelvin statement of the 2nd law.