Question

In isothermic process, which statement is wrong
A. Temperature is constant
B. Internal Energy is constant
C. No exchange of heat energy
D. (A) and (B) are correct

Answer 1

Hint:
In an Isothermal process in a thermodynamic system, the temperature is constant and at a constant temperature, the effect on the internal energy can be predicted by using the expression $U = f\left( T \right)$ . Also, the other parameters such as pressure, volume, heat energy, etc., vary with the given conditions of the system and surroundings.



Complete step by step solution:

An isothermal Process in thermodynamics is defined as the process during which the temperature $T$ of a system remains constant that’s why it is also referred to as a constant-temperature process.
i.e., In an Isothermal process, $T = constant$
and$\,Change{\text{ }}in{\text{ }}Temperature = \Delta T = 0$
Since the relationship between internal energy and temperature is: -
 $U = f\left( T \right)$ and as $T = constant$
 $ \Rightarrow U = constant$ which means options (A) and (B) are incorrect.
But heat energy is exchanged in an isothermal process between the system and its surroundings to keep the system temperature constant.
Graphically, the above situation is represented as: -

Thus, in the isothermal process, the exchange of heat energy is necessary to maintain the temperature constant.
Hence, the correct option is (C) No Exchange of Heat Energy.






Note:
 In this problem, to determine which law of an ideal gas obeys an isothermal change, use $\Delta T = 0$ and hence, analyze each and every given option carefully to give a precise explanation by simplifying ideal gas equation with respect to isothermal change and provide the exact reasons in support of your explanation.