The position of equilibrium

Z1) is never reached in an irreversible process.
Z2) is always reached in a reversible process.
Z3) is the same for pure reactants or pure products as starting materials.

1. Z3) only.
2. Z2) only.
3. Z1) and Z2) only.
4. Z1) and Z3) only.
5. Z1) only.

4.Z1) and Z3) only

To determine the correct answer, let's analyze each statement:

Z1) "The position of equilibrium is never reached in an irreversible process."
This statement implies that in an irreversible process, the reaction does not reach a state where the rate of the forward reaction is equal to the rate of the reverse reaction, which is the condition for equilibrium. Therefore, the position of equilibrium is not reached in an irreversible process.

Z2) "The position of equilibrium is always reached in a reversible process."
This statement suggests that in a reversible process, the reaction does reach a state of equilibrium where the rates of the forward and reverse reactions are equal. Therefore, the position of equilibrium is always reached in a reversible process.

Z3) "The position of equilibrium is the same for pure reactants or pure products as starting materials."
This statement indicates that the composition of the equilibrium mixture is independent of whether the reaction initially started with pure reactants or pure products. The position of equilibrium refers to the relative concentrations of reactants and products at equilibrium, and it does not depend on the starting materials.

Based on these explanations, the correct answer is:
2. Z2) only.
Because the position of equilibrium is always reached in a reversible process.

I don't think there is any process that is irreversible so I discard #1.

#2 is true.
#3 doesn't make sense to me. I don't know what it says.
Therefore, I would go with #2 only.