Question

The calorific value of fat is :
(A) less than that of carbohydrate and protein
(B) less than protein but more than carbohydrate
(C) less than carbohydrate but more than protein
(D) more than carbohydrate and protein

Answer 1

Hint: The measurement of energy or heat released when one unit weight or unit volume of a substance during complete combustion is known as Calorific value.

Complete step by step solution:
-The amount of heat energy that is present in food or fuel and which is determined by the complete combustion of a specified quantity occurring at constant pressure and in normal conditions is known as the Calorific value, or heating value or energy value.
-The unit of calorific value is kilojoule per kilogram that is kJ/kg.
-In the combustion process, water vapour is generated and the heat present in it can be recovered using certain techniques. If the heat contained in the water vapour could be recovered, it means that the substance has a high calorific value. If the heat contained in the water vapour could not be recovered, it means that the substance has a low calorific value.
-The efficiency of food or fuel depends on its calorific value. If the substance has a high calorific value, then it will also have high efficiency. If the substance has a low calorific value, then it will also have low efficiency. Hence we can say that the calorific value is directly proportional to its efficiency.

-The calorific values of some common food types are given below-

Category of food	Quantity of food (grams)	Calorific value (approximately)
		Kilojoules (kJ)	Kilocalories (kcal)
Dietary fibre	1	8	2
Polyhydric alcohols	1	10	2.4
Alcohols	1	29	7
Carbohydrates	1	17	4
Protein	1	17	4
Fats	1	37	9

-From the table above, we can see that the decreasing order of the calorific values between protein, fats, and carbohydrate is Fat $>$ Carbohydrate $>$ Protein.

So the correct answer is option D.

Note: Knowing the calorific value of the food we take helps us to carry out our day-to-day activities. It also helps us to determine the amount of energy we consume, transport, and require. The gas suppliers in our home require this information in determining the transportation charges. Humans also require calories to perform its basic and essential metabolic processes. Without calories, the body would stop working causing the death of the cells. Consuming only the required calories each day will lead to a healthy life. Too high or too low consumption of calories will cause health problems.