Answer:
(C) The number of microstates of system 2 is twice as high as those of system 1.
Explanation:
In thermal contact, energy is exchanged between the two systems until thermal equilibrium is reached.
In thermal equilibrium, the temperature of system one is always equal to temperature of system two.
Also from second law of thermodynamic;
The entropy of an isolated system never decreases: in equilibrium, the entropy stays the same; otherwise the entropy increases until equilibrium is reached.
Since the two boxes are in thermal equilibrium, the entropy of system 1 is equal to the entropy of system 2.
However, a microstate is a specific microscopic configuration of a thermodynamic system that the system may occupy with a certain probability in the course of its thermal fluctuations.
Since system 2 = twice system 1
Then, microscopic configuration of system 2 is equal to twice microscopic configuration of system 1.
P₂ (Box(A+B))= P₁(2A), since the two boxes are identical.
Therefore, the number of microstates of system 2 is twice as high as those of system 1.