Question

In a cyclic process, work done by the system is
A. Zero
B. More than the heat given to the system
C. Equal to the heat given to the system
D. Independent of the heat given to the system

Answer 1

Hint:
The thermodynamic system is the system that includes the change of the heat energy and the work from the system to the surrounding. Or from surrounding to the system.

Complete step by step answer:
The cyclic process is the process which has the same initial and the final state of the system. So, the energy of the system in its initial and final position is the same. So, the internal energy of the system is zero.
Consider the cyclic process in which the initial and the final state of the system is the same. Applying the first law of thermodynamic to the system:
$\mathrm{\Delta }U$ = Q+W … (I)
Where, \Delta U is the internal energy of the system, Q is the heat applied to the system and W is the work done by the system.

For cyclic process you have,
$\mathrm{\Delta }U$ = 0 … (II)

Substituting equation (II) in equation (I) you will get,

W = Q
So, the work done by the system is equal to the heat supplied to the system.
Option C is correct.

Note:
For normal processes, the work done is the product of the force and displacement.
So,
W=Fs
Where, F is the force and s is the displacement.
So, for cyclic process, s = 0
Thus, work done is zero.
But this is not true for the thermodynamic process.