How many BTUs are required to convert a pound of water at 32 degrees Fahrenheit to a pound of ice?

To understand why the conversion of one pound of water at 32 degrees Fahrenheit to a pound of ice requires 144 BTUs, it's important to consider the phase change involved in this process.

When water at 32°F freezes into ice, it undergoes a phase change from a liquid state to a solid state. During this phase change, the temperature of the water does not change; instead, energy is either absorbed or released. This energy involved in the phase change is known as latent heat. For water, the latent heat of fusion (the amount of energy required to convert ice at 32°F to water at the same temperature) is approximately 144 BTUs per pound.

Thus, to convert one pound of water at 32°F to one pound of ice at the same temperature, 144 BTUs of energy must be removed from the water. This is why the value of 144 BTUs is the correct answer. It specifically addresses the energy required to perform this process, while other options do not align with the established latent heat values for water.