Final answer:
None of the pairs listed will ideally form a solution. Toluene is a nonpolar solvent and will dissolve nonpolar substances like hexane, following the 'like dissolves like' rule based on similar intermolecular interactions.
Step-by-step explanation:
The student's question pertains to the solubility of substances and which pair would form a solution. According to the principle that 'like dissolves like', solutes will dissolve in solvents that have similar intermolecular forces. Toluene (C6H5-CH3) is a nonpolar solvent, so among the options provided, the substance that will dissolve in toluene is another nonpolar substance which is octane (C8H18).
Regarding the pairs mentioned in the question, the correct answer is not explicitly listed among the options provided. However, based on the 'like dissolves like' rule, sodium chloride (NaCl), being ionic and thus polar, would not dissolve in nonpolar toluene. Water and hexane, being polar and nonpolar respectively, would not form a solution. Ammonia is polar, which might make it seem miscible with toluene, but because toluene is nonpolar, ammonia would not dissolve well in it. None of the pairs listed will form an ideal solution, but if toluene were paired with another nonpolar substance like hexane, they would indeed form a solution because both share similar dispersion forces.