Pick out the correct statement.

A. The available energy in an isolated system for all irreversible (real) processes decreases

B. The efficiency of a Carnot engine increases, if the sink temperature is decreased

C. The reversible work for compression in non-flow process under isothermal condition is the change in Helmholtz free energy

D. All of the above

Answer: Option D

Solution(By Examveda Team)

All the given statements are correct the $${\left( {dG} \right)_{T,P}} < 0.$$
For irreversible process and the efficiency is inversely proportional to sink temperature for an carnot engine and by the definition of Helmholtz energy itself the change in Helmholtz energy represents the negative of work done in an reversible isothermal process.