Approximately how many BTUs are necessary to turn 1 pound of water at 212°F into steam at the same temperature?

To turn 1 pound of water at 212°F into steam at the same temperature, the process requires a significant amount of energy known as the heat of vaporization or latent heat. Specifically, it takes approximately 970 BTUs to convert 1 pound of water at its boiling point into steam without changing the temperature. This value reflects the energy required to break the hydrogen bonds between water molecules, allowing them to transition from the liquid phase to the gaseous phase.

The other choices reflect amounts of energy typically related to other processes, such as raising the temperature of water or other phase changes, but they do not represent the specific energy requirement for the phase change from liquid water to steam at 212°F. Thus, the correct answer focuses precisely on the heat of vaporization, confirming why 970 BTUs is necessary for this phase change.