Freezing point of a solution is smaller than that point of a solvent. It is due to : (a) \(\Delta H\) of solution and solvent is almost identical since intermolecular forces between solvent molecules are involved (b) \(\Delta S\) of solution (between solution and solid) is larger than that of the \(\Delta S\) of solvent (between solvent and solid) (c) \(\Delta S\) of the solution is smaller than that of the solvent (d) \(\Delta H\) of the solution is much higher than of solvent but \(\Delta S\) of solution is smaller than that of the solvent

Colligative properties are unique characteristics of solutions that depend on the number of solute particles rather than their specific identity. Key examples of colligative properties include boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure.

Understanding freezing point depression as a colligative property is crucial in many applications. When a solute is dissolved in a solvent, it disrupts the crystal lattice formation essential for freezing, thereby requiring a lower temperature to reach the solid state. This means that for a solution to freeze, the solidifying solvent molecules must be able to overcome the disruptive presence of the solute particles. It's this increase in disorder, represented as an increase in entropy, that is responsible for the lowering of the solution's freezing point compared to the pure solvent.

Enthalpy change, denoted as (ΔH), is a measure of the total heat content change within a system during a process at constant pressure. In terms of physical chemistry, when a substance transitions from one phase to another, such as from liquid to solid, there's an associated change in enthalpy.

Determining (ΔH) is essential for understanding the energy requirements during phase changes. For instance, during freezing, energy is released by the system as the molecules arrange into a more orderly structure. However, when a solute is introduced, the change in enthalpy isn't as dramatic in the process of freezing point depression. This is because the introduction of solute particles primarily affects entropy rather than enthalpy.

Entropy change ((ΔS)) quantifies the variation in randomness or disorder within a system during a thermodynamic process. Greater entropy signifies higher disorder. In the context of phase transitions, such as freezing, the entropy typically decreases as the system becomes more ordered.

However, in a solution, the introduction of solute creates a more disordered system compared to the pure solvent. As a result, the presence of solute particles increases the total entropy of the solution. Since a higher level of disorder is favored, the entropy term (ΔS), can explain why the freezing point of a solution is lower than the freezing point of the pure solvent. The higher entropy due to the solute's presence must be overcome to reach the ordered solid state, hence, a lower temperature (below the solvent’s freezing point) is necessary.

Thermodynamics in physical chemistry examines the principles that govern the energy and entropy changes associated with chemical processes and phase transitions. The fundamental laws of thermodynamics describe how these changes occur and predict the direction and spontaneity of these processes.

With respect to freezing point depression, thermodynamics helps explain why the addition of a solute results in the need for a lower temperature to attain the solid phase. The Second Law of Thermodynamics dictates that the total entropy of the universe must increase in a spontaneous process. Therefore, the increased disorder created by dissolving a solute aligns with this law and necessitates a modified (lower) freezing point for the solution.

A phase transition is a transformation of a substance from one state of matter to another, such as from liquid to solid (freezing), driven by changes in temperature and/or pressure. The transition involves breaking and forming intermolecular forces, and during this process, the enthalpy and the entropy of the system change.

When discussing the freezing point depression, it's clear that this phase transition is impacted not only by temperature but also by the compositional nature of the system. The presence of solute particles in a solvent interrupts the organized arrangement necessary for solid formation, which modulates the conditions (like temperature) necessary for the phase transition to occur. Thus, understanding the underlying enthalpic and entropic changes gives insight into the physical basis of freezing point depression.