Question

Specific heat of substance at m.pt. (or b.pt. or for isothermal process) and specific heat of a substance during adiabatic change respectively are

• A. 0, 0
• B. 0, $\infty$
• C. $\infty$, 0
• D. $\infty ,\infty$

Answer 1

The correct option is C $\infty$, 0

The amount of heat required to raise the temperature of unit mass of a substance by one degree celsius is known as specific heat. It is given by the ratio $\left(\frac{\partial H}{\partial T}\right)$
When at constant pressure, one phase of a substance is in equilibrium with other phase (during melting or boiling), the heat $\partial H$ is supplied to the system, and the temperature change $\partial T$ is zero as the heat supplied is utilized for the phase transition.
Hence, the specific heat is infinite. This is also true for the isothermal process.
During adiabatic process, no heat is supplied to system. The term $\partial H$ is zero. Hence the specific heat is zero.