Question

Which of the following statements is correct according to the second law of thermodynamics?

• A. All heat can be converted into work
• B. All heat cannot be converted into work
• C. Both (a) and (b) are correct.
• D. Both (a) and (b) are wrong.

Answer 1

The correct option is B All heat cannot be converted into work

From Kelvin-Planck statement, it is impossible to construct a heat engine that extracts heat and fully utilizes it to produce work.
In other words, efficiency of a heat engine can never be $100\%$. Hence, all the heat energy can not be converted to work.