Heat pumps do work on a refrigerant to reverse the normal flow of
a. electrical energy
b. potential energy
c. mechanical energy
d. thermal energy

The correct answer is "thermal energy".

Explanation:

Refrigeration: It is the process of rejecting heat from low temperature reservoir and then, transfer it to high temperature reservoir.

Here, the heat is taken from the colder body and reject it to hotter body. The sink is at the lower temperature. The source is at the higher temperature.

Thermal energy: It is the energy that comes from heat.

The difference between the heat engine and refrigeration is the operating temperature.

In heat engine, the heat is transferred from high temperature reservoir to the low temperature reservoir. Heat engine operates as a heat pump. It is just opposite of the refrigeration.

Therefore, heat pumps do work on a refrigerant to reverse the normal flow of thermal energy. The correct answer is (D).

the answer would be c

the earths atmosphere is made up of nitrogen and oxygen. solids can turn into gasses through a process called sublimation. sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.

hope this : d