Free energy

Decreases in all spontaneous (or irreversible) processes

Change during a spontaneous process has a negative value

Remains unchanged in reversible processes carried at constant temperature and pressure

All of the above

Answer

Answer: Option D

Answer: Option D

Solution:

Since for an spontaneous process

s > d U + P d V

For, constant temperature and constant pressure process the above equation can be written as

d (T S - U) > P d V \Rightarrow d (- A) > P d V \Rightarrow (d G)_{T, P} < 0.

For spontaneous process (irreversible). And

(d G)_{T, P} = 0

for, a reversible process.