Which description correctly defines a small calorie?

• A. The amount of heat energy that will raise the temperature of 1 gram of water 1°C.
• B. The amount of heat energy that will raise the temperature of 1 kilogram of water 1°C.
• C. The heat required to raise 10 grams of water by 1°C.
• D. The heat required to raise 100 grams of water by 1°C.

Answer: (A)

A small calorie is defined as the amount of heat needed to raise the temperature of 1 gram of water by 1°C. This reflects water’s specific heat capacity, which is 1 cal per gram per degree Celsius. That’s why this description is the exact definition of a small calorie.

In contrast, raising 1 kilogram of water by 1°C describes a kilocalorie (often called a Calorie in nutrition), which equals 1000 small calories. The other options talk about different masses (10 g or 100 g) and aren’t the standard definition for the small calorie. For reference, 1 small calorie is about 4.184 joules.