The increasing order of the boiling points for the following compounds is : C2H5OH(I) C2H5Cl(II) C2H5CH3(III) C2H5OCH3(IV)

The boiling point of a compound depends on the strength of intermolecular forces. The stronger the intermolecular forces, the higher the boiling point.

The given compounds are:

(I) C2H5OH (Ethanol)
(II) C2H5Cl (Chloroethane)
(III) C2H5CH3 (Propane)
(IV) C2H5OCH3 (Methoxyethane)

Let's analyze the intermolecular forces:

• (I) C2H5OH: Ethanol exhibits hydrogen bonding, a strong intermolecular force due to the presence of the hydroxyl (-OH) group. Hydrogen bonding is significantly stronger than dipole-dipole interactions or London dispersion forces.
• (II) C2H5Cl: Chloroethane has a dipole-dipole interaction due to the polar C-Cl bond. Dipole-dipole interactions are stronger than London dispersion forces but weaker than hydrogen bonding.
• (III) C2H5CH3: Propane is a nonpolar molecule, exhibiting only weak London dispersion forces.
• (IV) C2H5OCH3: Methoxyethane has a dipole-dipole interaction due to the polar C-O bond, but it does not have hydrogen bonding because the oxygen is not directly bonded to a hydrogen atom. Therefore, its intermolecular forces are weaker than ethanol's hydrogen bonding.

Based on the strength of intermolecular forces, the increasing order of boiling points is:

(III) < (IV) < (II) < (I)

Propane (III) has the weakest London dispersion forces, followed by methoxyethane (IV) with its dipole-dipole interactions. Chloroethane (II) has stronger dipole-dipole interactions than methoxyethane. Ethanol (I) has the highest boiling point due to its strong hydrogen bonding.