Adding p-nitrotoluene to freezing point naphthalene will lower the freezing point of the naphthalene. This is due to the phenomenon known as freezing point depression.

Here's why:

* Freezing point depression: This is a colligative property, meaning it depends on the number of solute particles present in a solution, not their identity.

* Solute and solvent: In this case, naphthalene is the solvent (the substance that dissolves the other), and p-nitrotoluene is the solute (the substance that dissolves).

* Disruption of crystal lattice: When you add p-nitrotoluene to naphthalene, the p-nitrotoluene molecules disrupt the orderly arrangement of naphthalene molecules in the crystal lattice. This makes it harder for the naphthalene molecules to form a solid structure.

* Lower freezing point: As a result, the temperature at which the naphthalene solution will freeze is lower than the freezing point of pure naphthalene.

Key points:

* The amount of freezing point depression depends on the concentration of the solute (p-nitrotoluene). The higher the concentration, the greater the depression.

* This effect is useful for determining the molecular weight of a solute (using a technique called cryoscopy).

Let me know if you would like to know more about freezing point depression or other colligative properties!