One calorie is the amount of heat required to raise how many grams of water by one degree Celsius?

One calorie is defined as the amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celsius. This definition stems from the foundational concepts of thermodynamics and heat transfer. The calorie is a unit of energy that specifically relates to the heat energy required for water because of its importance in biological systems and its abundance on Earth.

When water is heated, the molecular motion increases, leading to a rise in temperature. The precise relationship defined by the calorie allows scientists and researchers to measure heat transfer in various processes, making it a fundamental unit in both chemistry and biology. Understanding this measurement is crucial, especially in fields such as nutrition, where energy content in food is often measured in calories.

The other choices do not align with the standard definition of a calorie, as they suggest different quantities of water rather than the singular gram which is the basis of this definition.