Which of the following substances has the highest amount of energy in joules per unit weight?

Fats have the highest amount of energy in joules per unit weight compared to carbohydrates, proteins, and vitamins. This is because fats have more carbon-hydrogen bonds in their molecular structure, which store more energy than the oxygen-hydrogen bonds found in carbohydrates and proteins. When fats are broken down through a process called metabolism, they release more energy per unit weight than carbohydrates and proteins. Therefore, foods that are high in fat tend to have a higher caloric value than foods that are high in carbohydrates or proteins. Vitamins, on the other hand, are essential micronutrients that do not provide energy when metabolized and therefore are not a significant source of calories.