Answer:

The solutions which obey Raoult’s law over the entire range of concentration are known as ideal solutions. The ideal solutions have two other important properties. The enthalpy of mixing of the pure components to form the solution is zero and the volume of mixing is
also zero, i.e.,
ΔmixH = 0,  ΔmixV = 0

ideal behaviour of the solutions can be explained by considering two components A and
B. In pure components, the intermolecular attractive interactions will be of types A-A and B-B, whereas in the binary solutions in addition
to these two interactions, A-B type of interactions will also be present.
If the intermolecular attractive forces between the A-A and B-B are nearly equal to those between A-B, this leads to the formation of ideal
solution. example are  Solution of n-hexane and n-heptane, bromoethane and chloroethane, benzene and toluene, etc

When a solution does not obey Raoult’s law over the entire range of concentration, then it is called non-ideal solution.
example Mixtures of ethanol and acetone.

Collegative properties of solution are the properties which depend upon the number of particles present in the solution. When the solute does not undergo any chemical/physical change, the molecular mass of the solute as obtained from the colligative properties is equal to its stoichiometric value.

Therefore in many cases where the solute associate or dissociate in solution certain abnormal values of colligative properties are obtained the value of molecule masses calculated based on colligative properties in such cases will also be abnormal.

osmotic pressure is proportional to the molarity, C of the solution at a given temperature T. Thus:
Π = C R T
Here Π is the osmotic pressure and R is the
gas constant.
Π = (n2 /V) R T