Which of the following crystals will be soluble in solvents having highvalues of dielectric constant?

NaCl

the answer is 2. NaCl is soluble in solvents with high dielectric constants.

Iodine (I₂) and solid ammonia (NH₃) are both molecular crystals, and the molecules in the crystal are held together by weak van der Waals forces. These forces are not strong enough to be overcome by the forces of a polar solvent, so I₂ and NH₃ will not dissolve in a polar solvent.

Sodium chloride (NaCl) is an ionic crystal, and the ions in the crystal are held together by strong ionic bonds. These bonds can be overcome by the forces of a polar solvent, so NaCl will dissolve in a polar solvent.

Here is a table summarizing the solubility of the three crystals in polar solvents: