Question

If Q, E and W denote respectively the heat added, change in internal energy and the work done by a closed cycle process, then:
A) $E = 0$
B) $Q = 0$
C) $W = 0$
D) $Q = W = 0$

Answer 1

Hint: In a closed thermodynamic cycle, the thermodynamic states within the system remain the same. That is the properties are transferring only within the system. Thus when we look as a whole system there are no changes happening outside the system.

Complete step by step answer:
Let’s discuss all the terms given in the question in detail,
It is given in the question that the process is a closed cyclic process. What is a closed cyclic process?

In a closed cyclic process the thermodynamic state of the whole system is the same at the start and at the end of the process. It produces a closed loop in a process diagram.
To achieve a cyclic process, the thermodynamic properties like heat and work done in a thermodynamic process must be equal to each other; but the value of these properties need not to be equal to zero.
That is, $Q = W$
Where $Q$ is the heat added to the thermodynamic system
$W$ is the work done in the thermodynamic system

In a closed thermodynamic cyclic process, the energy levels at start and end of the process must be equal. That is, internal energy remains the same after the thermodynamic process. From these details we can understand that the change of energy within the system or internal energy is zero.
That is, Change in internal energy within a closed thermodynamic cycle, $E = 0$

So, the correct answer is option (A), $E = 0$.

Note: A closed system can transfer energy with its surrounding area through Heat and work transfer. That is, the work and heat are the two medium through which energy can be exchanged over the framework limit of the closed system.