Based on solute-solvent interaction, the solute which will be most soluble in n-octane is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \(C_6H_{14}\)
A solute dissolves in a solvent when the intermolecular interactions are similar in the two: polar solutes dissolve in polar solvents and non-polar solutes in non-polar solvents (like dissolves like). n-Octane, \( \ce{C8H18} \), is a non-polar hydrocarbon held together only by weak London (dispersion) forces.
Hexane, \( \ce{C6H14} \), is also a non-polar hydrocarbon with the same kind of forces. Its molecules mix with octane molecules without breaking any stronger attractions, so hexane is completely miscible with n-octane and is the most soluble of the four.
Why the other options are incorrect
Option (2) KCl — Incorrect. An ionic solid dissolves only where ion–dipole attractions can pay for breaking its strong lattice; non-polar octane offers none, so KCl is practically insoluble.
Option (3) \(CH_3CN\) — Incorrect. Acetonitrile is a polar molecule with strong dipole–dipole attractions, which octane cannot replace.
Option (4) \(CH_3OH\) — Incorrect. Methanol molecules are held by hydrogen bonds; octane cannot form hydrogen bonds, so little methanol dissolves.
NCERT (2026-27 edition):
Solubility of a Solid in a Liquid
