Why does entropy increase in an irreversible process?

Hint :entropy is a state function. This means it does not depend upon the path followed to change the state. Entropy is positive for the irreversible processes. The calculation of an irreversible process can be carried out by converting these irreversible processes into many reversible ones.

Complete Step By Step Answer:
Entropy is defined as the property of a system that measures the degree of disorder or randomness of a system. When a system becomes more disordered, the positions of the molecules become less predictable, and the entropy increases. The entropy of a substance is lowest in the solid phase and highest in the gas phase. Entropy is a non-conserved property, unlike energy. Energy can be conserved but entropy cannot. Entropy is related to the distribution or spread of energy among the available molecular energy levels.
An irreversible process increases the entropy. This is because entropy is a state function, the change in entropy of the system is the same, whether the process is reversible or irreversible. Energy always flows downhill, which causes entropy to increase. Also the greater the number of energy levels, the larger is the entropy. Increasing the energy of the system increases the entropy of that system. Because it allows higher energy levels to be significantly occupied. And more energy level to be occupied when there is an increase in the volume of a system at constant energy.

Note :
This question can also be answered by the second law of thermodynamics. it states that the entropy change of the universe increases for an irreversible or a spontaneous process. Entropy is represented as $ S $ , so for the irreversible process the change in entropy is $ \Delta {S_{irreversible}} > 0 $ . The entropy of a system is a thermodynamic variable.