State which of the following statements is true for an ideal solution.

Options

A. `Delta H_("mix") = (+)ve, DeltaV_("mix") = (+)ve`
B. `P_("Actual") lt P_("Theoretical")`
C. `Delta G_("mix") = (-)ve, DeltaS_("mix") = (+)ve`
D. `Delta G_("mix") = O,DeltaH_("mix") = O`

Explanation

To determine which statement is true for an ideal solution, we need to analyze the characteristics of ideal solutions. Here’s a step-by-step breakdown of the concepts involved:

### Step 1: Understanding Ideal Solutions
An ideal solution is one where the interactions between different molecules are similar to the interactions between the same type of molecules. This means that the enthalpy of mixing (ΔH_mix) is zero because there is no heat absorbed or released during the mixing process.

**Hint:** Recall that in an ideal solution, the intermolecular forces between different components are similar to those in the pure components.

### Step 2: Change in Volume
In an ideal solution, the change in volume upon mixing (ΔV_mix) is also zero. This is because the volume occupied by the solution is the sum of the volumes of the individual components, and there is no contraction or expansion.

**Hint:** Consider how the volume behaves when two substances mix without any change in intermolecular interactions.

### Step 3: Gibbs Free Energy Change
For an ideal solution, the Gibbs free energy change (ΔG) for mixing is negative, indicating that the mixing process is spontaneous. This is a result of the increase in entropy.

**Hint:** Remember that a negative ΔG indicates a spontaneous process, often linked to an increase in disorder (entropy).

### Step 4: Entropy Change
The entropy change (ΔS) for mixing is positive in an ideal solution. This is because mixing increases the randomness or disorder of the system.

**Hint:** Think about how mixing different substances increases the number of possible arrangements of the molecules.

### Step 5: Pressure of the Solution
In an ideal solution, the pressure of the solution (P_solution) is equal to the pressure of the ideal gas (P_ideal). This reflects the behavior of the solution under ideal conditions.

**Hint:** Consider the relationship between pressure and the behavior of gases and solutions.

### Conclusion
Based on the analysis above, the correct statement for an ideal solution is: **"ΔG is negative for mixing and ΔS is positive for mixing."**

This means that the third option is true.