Based on solute-solvent interactions, arrange the following compounds in order of increasing solubility in n-octane and provide an explanation:

Cyclohexane, KCl, CH3OH, CH3CN

In n-octane, which is a nonpolar solvent, solutes will dissolve based on their ability to interact with nonpolar molecules. The solubility of a solute in a solvent depends largely on the strength of the intermolecular forces between the solute molecules and the solvent molecules.

Here's the breakdown of the solutes you provided based on their interactions with n-octane:

Cyclohexane - Cyclohexane is a nonpolar molecule, similar in nature to n-octane. It can dissolve readily in n-octane due to favorable dispersion forces between its nonpolar molecules and those of n-octane. Therefore, cyclohexane will have the highest solubility in n-octane among the options provided.
KCl (Potassium Chloride) - KCl is an ionic compound, composed of potassium cations (K+) and chloride anions (Cl-). Ionic compounds generally do not dissolve well in nonpolar solvents like n-octane because the solvent cannot effectively solvate the ions due to their strong electrostatic interactions. Hence, KCl will have the lowest solubility in n-octane among the options provided.
CH3OH (Methanol) - Methanol is a polar molecule due to the electronegativity difference between carbon and oxygen, resulting in a partial negative charge on the oxygen atom and a partial positive charge on the carbon atom. While methanol is not as polar as water, it still exhibits some degree of polarity, enabling it to form hydrogen bonds with itself and other polar molecules. However, in n-octane, the polar interactions between methanol and n-octane are not as strong as those between methanol molecules or with water. Therefore, methanol's solubility in n-octane would be moderate compared to the other options.
CH3CN (Acetonitrile) - Acetonitrile is a polar solvent due to the electronegativity difference between carbon and nitrogen. Like methanol, it can participate in dipole-dipole interactions and hydrogen bonding. However, acetonitrile is less polar than methanol. Its solubility in n-octane would be higher than KCl due to the presence of polar interactions, but lower than methanol due to its lower polarity.
So, the order of increasing solubility in n-octane would be:

KCl (lowest solubility)
CH3CN
CH3OH
Cyclohexane (highest solubility)