Question

1 calorie $=$
(A) Amount of heat energy required to transform 1kg of ice into water at $0^\circ C$
(B) Amount of heat energy required to raise the temperature of water through $1^\circ C$
(C) Amount of heat required to raise the temperature of 1g of water through $1^\circ C$
(D) Quantity of work done at atmospheric pressure

Answer 1

The calorie is a unit of energy. It is related to raising the temperature of water as the amount of a form of energy which will be required to do the said work.

Complete Step-by-Step solution:
The calorie in general, is a unit of energy, more specifically heat energy (as it isn’t used to quantify other forms of energy). This means if we are to heat 1 g of water from say 1 degree Celsius to 2 degree Celsius, we must have added 1 calorie of heat energy.
It can be defined as the amount of heat energy required to raise the temperature of 1 g of water through $1^\circ C$. It is equal to $4.184$ joules.
A derivative of the unit calorie is the kilocalorie, also written as Calorie (the difference is the capital letter C). The kilocalorie or Calorie is exactly equal to 1000 calorie and hence, is equal to 4184 J. The kilocalorie due to its moderate nature (not too large a quantity and not too small), it is used as the unit of food energy. Observing the back of a cereal box, or other packaged food substance, the energy is often quantified using the kilocalorie abbreviated as kcal.
However, the calorie has been defined in various ways. It can more accurately be defined as the amount of heat required to raise the temperature of 1 gram of water from $14.5^\circ C$ to $15.5^\circ C$.

Hence the correct answer is option C.

Note: For clarity, the specification of the temperature was made in the more accurate form because of the temperature dependence of specific heat capacity. The specific heat capacity of water at zero degree Celsius is not the same as that at 20 degree Celsius, hence, the heat required to raise it by one degree is different at the temperatures.