Question

The mixing of non-reacting gases is generally accompanied by
A. Decrease in entropy
B. Increase in entropy
C. Increase in enthalpy
D. Decrease in temperature

Answer 1

Hint: According to the second law of thermodynamics "the entropy of the universe increases for an irreversible process".
Entropy stays constant for a reversible process.

Complete step-by-step answer: Entropy is the measure of the extent of disorderness in a state of a thermodynamic system.
It demonstrates the anomaly or absence of uniformness in the structure of a thermodynamic system.
This is signified by ‘S’.
It is an extensive property as the calculation of entropy or entropy change relies on the quantity of matter present in a thermodynamic system.
Entropy is a state function as its value does not depend on the path by which the system has attained a specific state.
It depends on only the initial and final state of the system.
According to the second law of thermodynamics, for an irreversible reaction the entropy increases.
In the given question, we have a mixture of non-reacting gases.
Let us consider gases A and B which are non-reacting and are mixed in a given container.
This is a spontaneous reaction and thus an irreversible process.
According to the kinetic theory of gases, the gas molecules are presumed to be moving continuously in different directions with different velocities. So, they keep colliding with one another as well as on the walls of the container.
Since the gases are non-reactive so they will not react with each other.
The gas molecules of both gases A and B will collide with each other and also with the wall of the container.
This will increase the degree of disorderliness of the gases.
So, this will result in a rise in entropy.

So, option B is correct.

Note: Every spontaneous process is irreversible which increases the entropy of the universe.
With the increase in the spontaneity in a system, the degree of disorderliness increases and thus entropy increases.