One BTU is the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit.

One BTU is the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit.

• A. One kilogram of water by one degree Celsius
• B. One pound of water by one degree Fahrenheit
• C. One liter of water by one degree Fahrenheit
• D. One pound of water by one degree Celsius

Answer: (B)

The main idea here is the definition of a BTU in HVAC practice: it is the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit. This specific pairing—pounds for mass and Fahrenheit for the temperature change—is what defines a BTU, using water as the reference substance because its specific heat is well established. Therefore, describing it as one pound of water rising by one degree Fahrenheit exactly matches the standard definition. The other options mix different units (kilograms with Celsius, liters with Fahrenheit, or pounds with Celsius), which do not fit how a BTU is defined in this context.

The main idea here is the definition of a BTU in HVAC practice: it is the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit. This specific pairing—pounds for mass and Fahrenheit for the temperature change—is what defines a BTU, using water as the reference substance because its specific heat is well established. Therefore, describing it as one pound of water rising by one degree Fahrenheit exactly matches the standard definition. The other options mix different units (kilograms with Celsius, liters with Fahrenheit, or pounds with Celsius), which do not fit how a BTU is defined in this context.