ANS:D - all (a), (b) & (c)

The correct answer is: "all (a), (b) & (c)." The heat of solution refers to the amount of heat energy absorbed or released when a solute dissolves in a solvent to form a solution. It depends on several factors:

1. Nature of Solvent: Different solvents have different intermolecular forces and interactions with solutes. The heat of solution can vary depending on whether the solvent-solute interactions are exothermic (heat is released) or endothermic (heat is absorbed). For example, water (a polar solvent) tends to form stronger interactions with polar solutes compared to non-polar solvents.
2. Concentration of Solution: The heat of solution can also depend on the concentration of the solution. In some cases, the heat of solution may vary with concentration due to changes in the solvent-solute interactions as the concentration changes. For example, some solutions may become more or less exothermic as the concentration increases.
3. Nature of Solute: Just like solvents, different solutes have different intermolecular forces and interactions with solvents. The nature of the solute can affect the strength and type of interactions with the solvent, thus influencing the heat of solution. For instance, polar solutes tend to dissolve more readily in polar solvents compared to non-polar solutes.