Which among the following purification methods is based on the principle of "Solubility" in two different solvents?

IUPAC name of following compound is :

The solution from the following with highest depression in freezing point/lowest freezing point is

Given below are two statements:

Statement - I: Since Fluorine is more electronegative than nitrogen, the net dipole moment of $$\mathrm{NF}_3$$ is greater than $$\mathrm{NH}_3$$.

Statement - II: In $$\mathrm{NH}_3$$, the orbital dipole due to lone pair and the dipole moment of $$\mathrm{NH}$$ bonds are in opposite direction, but in $$\mathrm{NF}_3$$ the orbital dipole due to lone pair and dipole moments of N-F bonds are in same direction.

In the light of the above statements, choose the most appropriate from the options given below: