Question

Which one of the following substances has the highest specific heat capacity at room temperature and atmospheric pressure.
A) Water
B) Ice
C) Aluminium
D) Mercury

Answer 1

Hint: Specific heat of a substance can be defined as the heat needed to raise the temperature of a body by unity. Atmospheric pressure is the pressure acting on everything by the earth’s atmosphere. So the specific heat of a body is dependent upon both the temperature and atmospheric pressure.

Complete step by step answer:
The specific heat of a body of unit mass is defined as the heat required to raise the temperature of a body by one unit. We can write specific heat as,
$c=\dfrac{Q}{m\Delta T}$
Where, Q is the heat supplied.
c is the specific heat.
$\Delta T$ is the temperature change of the body.
m is the mass of the substance.
It is very clear that the specific heat of a substance is dependent upon the temperature. It also depended upon the pressure. As the pressure increases more heat is required to increase the temperature of the body.
At room temperature and at atmospheric pressure, the specific heat of Aluminium is \[0.897\text{ }J{{g}^{-1}}{{K}^{-1}}\], the specific heat for mercury is \[0.139\text{ }J{{g}^{-1}}{{K}^{-1}}\]. For ice and water which is the same substance at different phases, for ice the specific heat is \[\text{2}\text{.108 }J{{g}^{-1}}{{K}^{-1}}\] and for water is \[4.187\text{ }J{{g}^{-1}}{{K}^{-1}}\].
So clearly water has the maximum specific heat among the options at room temperature and at atmospheric pressure.
So, the answer to the question is option (A) Water.

Note: Molar Specific Heat:- It is defined as the heat needed to raise the temperature of one mole of a substance by unity. $Q=nC\Delta T$. Its unit is $J{{\left( mol \right)}^{-1}}{{K}^{-1}}$.
Specific Heat at constant volume: The heat required to raise the temperature of a body of unit mass by 1 unit at constant volume.
Specific Heat at constant pressure: The heat required to raise the temperature of a body of unit mass by 1 unit at constant pressure.