Question

Define specific heat capacity of a substance. Mention its unit.

Answer 1

As a very first step, one could define the term heat capacity. Then, you could give how specific heat capacity is different from heat capacity of a substance. Thus, you could clearly get a definition for specific heat capacity. After that you could recall the unit (preferably the SI unit) for this quantity.

Complete step-by-step answer:
In the question we are asked about the specific heat capacity of a substance and we are also asked to give its unit.
Before defining the specific heat capacity let us define the heat capacity of a substance. Heat capacity could be defined as the amount of heat that is supplied to a certain mass of a substance so as to result in one degree change in temperature. This is basically a physical property of matter.
Specific heat capacity is specific, that is, it is defined as the heat capacity of a unit gram of substance.
So, it is the amount of energy that is required by one unit mass of a substance to cause a change in temperature by unity. Its SI unit is given by joule per Kelvin per kilogram$\left( J{{K}^{-1}}k{{g}^{-1}} \right)$.
This quantity varies with temperature and is also different for different states of matter.

Note: There are certain contexts in which the specific heat is defined as the ratio of the specific heats of a substance at a particular temperature and another reference substance at certain reference temperature. Specific heat in this particular context is similar to specific gravity.