Question

Which among the following substances has the greatest specific heat?
A. Iron
B. Water
C. Copper
D. Mercury

Answer 1

Hint:- Specific Heat of a substance can be defined as the heat needed to raise a body's temperature 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 temperature and the atmospheric pressure.

Complete step-by-step solution :
The Specific Heat of a body of unit mass is defined as the heat required raising a body's temperature by one unit. We can write specific heat as,
${\rm{C}}\; = \;\dfrac{{\rm{Q}}}{{{\rm{m }}\Delta {\rm{T}}}}$
Where Q is the heat supplied.
C is the Specific Heat.
$\Delta {\rm{T}}$ is the temperature change of the body.
m is the mass of the substance.
The Specific Heat of a substance is dependent upon the temperature and pressure. It also depended upon the pressure. If the pressure is increased, more heat is required to increase the temperature of the body.
The specific heat of iron is $0.450\;j/^\circ {\rm{C g}}$ the specific heat for mercury is $0.140\;j/^\circ {\rm{Cg}}$, and water specific heat is $4.18{\rm{j/}}^\circ {\rm{C g}}$, for copper, the specific heat is $0.385\;j/^\circ {\rm{Cg}}$. So clearly, water has the maximum specific heat among the options at room temperature and atmospheric pressure.
So, the answer to the question is an option (B) Water.

Note:-
Molar Specific Heat is defined as the heat needed to raise one mole of a substance's temperature by unity. ${\rm{Q}}\;{\rm{ = }}\;n{\rm{C}}\Delta {\rm{T}}$. Its unit is ${\rm{J/mol K}}$. Specific heat at constant volume: The Heat required raising the temperature of a body of unit mass by 1 unit at constant volume
Specific heat at constant volume: The Heat required raising 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 is constant.