Which of the following is not a correct statement about enthalpy of solution?

Options

A. a. For most ionic compounds, `DeltaH_("soln.")^(@)` is positive and the dissociation process is endothermic.
B. b. Solubility of most salts increases with increase in temperature.
C. c.If the lattice enthalpy is very high, the dissolution of compound becomes very easy.
D. d.Enthalpy of solution is determined by the selective values of the lattice enthalpy and hydration enthalpy.

Explanation

To determine which of the statements about the enthalpy of solution is not correct, let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Understanding Enthalpy of Solution**:
- The enthalpy of solution (ΔH_solution) is the heat change that occurs when a solute dissolves in a solvent at constant pressure. It can be either positive (endothermic) or negative (exothermic).

2. **Analyzing Statement A**:
- **Statement A**: "For most ionic compounds, ΔH_solution is positive and the dissociation process is endothermic."
- When ionic compounds dissolve, they typically require energy to break the ionic bonds (endothermic process). This energy requirement often results in a positive ΔH_solution.
- **Conclusion**: This statement is correct.

3. **Analyzing Statement B**:
- **Statement B**: "Solubility of most salts increases with an increase in temperature."
- Generally, as temperature increases, the kinetic energy of the solvent molecules increases, allowing more solute to dissolve. This is true for many salts.
- **Conclusion**: This statement is correct.

4. **Analyzing Statement C**:
- **Statement C**: "If the lattice enthalpy is very high, the dissolution of the compound becomes very easy."
- High lattice enthalpy means that a significant amount of energy is required to break the ionic bonds in the solid state. Therefore, if the lattice enthalpy is high, it is actually more difficult for the compound to dissolve.
- **Conclusion**: This statement is incorrect.

5. **Analyzing Statement D**:
- **Statement D**: "Enthalpy of solution is determined by the selective values of lattice enthalpy and hydration enthalpy."
- The enthalpy of solution is indeed influenced by both lattice enthalpy (energy required to separate ions) and hydration enthalpy (energy released when ions are surrounded by water molecules).
- **Conclusion**: This statement is correct.

### Final Answer:
The statement that is not correct about the enthalpy of solution is **Statement C**: "If the lattice enthalpy is very high, the dissolution of the compound becomes very easy."