Gas specifications may be measured in which unit?

The correct answer is BTU, which stands for British Thermal Unit. This unit is widely used in the energy sector to measure the heating value of fuels, including natural gas. One BTU is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. This makes it particularly relevant for comparing the energy content of various gas sources.

Using BTUs provides a consistent way to assess energy output and efficiency when dealing with gas, which is essential for applications in cooking, heating, and other energy uses. This emphasis on heating value aligns perfectly with gas specifications because they often focus on the energy potential of a fuel.

Other units such as Joules, Calories, and Watt-hours serve specific purposes related to different forms of energy measurement, but they do not focus on gases in the same way BTUs do. For example, Joules and Calories are often used in chemistry and physics to measure energy but are less common when discussing fuel energy specifications. Watt-hours measure electrical energy, not thermal energy from gases. Therefore, BTU is the most appropriate unit for gas specifications.