Question

What is the definition of 1 calorie?

(a) It is the heat required to raise the temperature of 1g of water from 14.5°C to 15.5°C at 760mm Hg

(b) It is the heat required to raise the temperature of 1g of any substance by 14.5°C to 15.5°C at 760mm Hg

(c) It is the heat required to raise temperature of 1g of water by 1°C at 760mm Hg

(d) It corresponds to the heat supplied at 760mm Hg for 1°C raise in temperature

I got this question during an online interview.

Question is from Thermal Properties of Matter in division Thermal Properties of Matter of Physics – Class 11

Answer 1

Right answer is (a) It is the heat required to raise the temperature of 1g of water from 14.5°C to 15.5°C at 760mm Hg

Easy explanation: A calorie is the unit of energy and is defined as the amount of heat required to raise the temperature of 1g of water from 14.5°C to 15.5°C at 760mm Hg.                                                                  Its value is 4.18 joules.                                                                                                                                Note that the calories we read behind food packets correspond to the amount of heat that quantity of food provides to our body which it uses for functioning.