How many calories are equivalent to 1 BTU?

The correct choice indicates that 1 BTU (British Thermal Unit) is equivalent to approximately 252 calories. This relationship arises from the defined measurements of energy.

A BTU is the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit at constant pressure. The calorie, while a smaller unit of energy, is defined as the amount of energy needed to raise the temperature of one gram of water by one degree Celsius.

To convert between these units, one must recognize that 1 BTU is roughly equal to 252 calories based on the differences in the definitions of the units and the mass of water involved in the thermal processes. This conversion facilitates the understanding of how energy is measured in various contexts, including heating and cooling systems.