Final answer:
1 gram of alcohol (ethanol) contains approximately 7 kilocalories (kcals), compared to other substances like fat, carbohydrates, and protein which have different kcals per gram.
Step-by-step explanation:
1 gram of alcohol, which is not a nutrient, contains approximately 7 kilocalories (kcals). This value is specific to ethanol (C₂H₅OH), which is a common type of alcohol used as a biofuel. For comparison, 1 gram of fat contains 9.3 kcals, 1 gram of carbohydrate or protein each contain about 4.1 kcals, and 1 gram of ethanol has an energy density of about 7.1 kcals.
Knowing the energy contents of different substances can be useful when comparing the energy provided by various fuels and food components.