A certain mass of solid substance is heated for a period of 50 min. Its heating curve is shown below :

From the graph, which one of the following statement is correct?

1. The boiling point of the given substance is 40°C.
2. The specific latent heat of fusion of substance is the same as the specific latent heat of vaporisation.
3. The substance has a higher specific heat capacity in solid state than that in liquid state.
4. The substance has a lower specific heat capacity in solid state than that in liquid state.

The substance has a higher specific heat capacity in solid state than that in liquid state

Reason — From graph, 40°C is the melting point of the substance. It takes 10 mins for melting for temperature change of 20°C (i.e.,40°-20°) and takes 10 mins for boiling for temperature change of 40°C (i.e., 80°-40°).

Hence, the latent heat of fusion is less than the latent heat of vapourisation

From relation,

Q = m x c x △T

C ∝ $\dfrac{1}{\Delta\text{T}}$

So, from graph, the specific heat capacity in solid state is greater than that in liquid state.