Ideal solution is a hypothetical solution that exhibits certain characteristics under specific conditions. The characteristics of an ideal solution are:

1. Zero heat of mixing: In an ideal solution, there is no heat released or absorbed when the components are mixed together. This means that the enthalpy change of mixing is zero. This condition implies that the intermolecular forces between the components are similar in strength and nature.

2. Zero volume change: In an ideal solution, there is no change in volume when the components are mixed together. This means that the volume of the solution is equal to the sum of the volumes of the individual components. This condition implies that the components have similar molecular sizes and do not experience significant volume interactions.

3. Raoult's Law: An ideal solution obeys Raoult's Law, which states that the partial pressure of each component in the vapor phase is directly proportional to its mole fraction in the liquid phase. This implies that the vapor pressure of each component in the solution is proportional to its concentration.

Explanation of the answer:

a) Zero heat of mixing: When two components have similar intermolecular forces, there is no heat released or absorbed during the mixing process. This indicates that the interactions between the molecules of the two components are similar in nature and strength. Consequently, the enthalpy change of mixing is zero, resulting in a zero heat of mixing.

b) Zero volume change: When two components have similar molecular sizes and do not experience significant volume interactions, there is no change in volume when they are mixed together. This means that the volume of the solution is equal to the sum of the volumes of the individual components. Therefore, an ideal solution has a zero volume change upon mixing.

c) Raoult's Law: An ideal solution obeys Raoult's Law, which states that the partial pressure of each component in the vapor phase is directly proportional to its mole fraction in the liquid phase. In other words, the vapor pressure of each component in the solution is proportional to its concentration. This behavior is observed when the intermolecular forces between the components are similar in strength and nature, leading to an ideal solution.

In summary, an ideal solution is formed when the components have zero heat of mixing, zero volume change, and obey Raoult's Law. These characteristics indicate that the intermolecular forces, molecular sizes, and concentrations of the components are similar, resulting in an ideal mixing behavior.