Question

in a heat pump, unlike a heat engine, ______.
o work is used to heat a low - temperature region and cool a high - temperature region
o work is used to cool a low - temperature region and heat a higher - temperature region
o all the heat energy is converted into work

Explanation:

A heat pump is a device that uses work input to transfer heat from a low - temperature reservoir to a high - temperature reservoir. In contrast, a heat engine extracts heat from a high - temperature source, converts part of it into work, and rejects the remaining heat to a low - temperature sink. The second law of thermodynamics states that heat cannot spontaneously flow from a cold to a hot body, so work is needed for the heat pump operation. Option 3 is incorrect as per the second law (not all heat can be converted to work). Option 1 is wrong because the heat pump's purpose is to heat the high - temperature region (e.g., heating a house in winter).

Answer:

work is used to cool a low - temperature region and heat a higher - temperature region