Several processes are described. Indicate whether each is reasonably modeled as reversible, and if not, indicate what aspect of the process makes it irreversible.

A. The inside of a refrigerator is at exactly 31.9°F. A glass of room temperature water is placed inside the refrigerator and left there until it is frozen.

B. The inside of a refrigerator is at exactly 31.9°F. A glass containing an equilibrium mixture of ice and water is placed inside the refrigerator and left there until it is frozen.

C. The inside of a refrigerator is at exactly 32.1°F. A glass containing an ice–water mixture is placed inside the refrigerator and left there until the ice is all melted.

D. A diver is 1000 feet below the surface of the ocean, where the pressure is 31 atm. She rapidly ascends to the surface, where the pressure is 1 atm.

E. A diver is 1000 feet below the surface of the ocean, where the pressure is 31 atm. Over a period of half an hour she gradually ascends to the surface, where the pressure is 1 atm.