Identify the solution which is nearly ideal in behaviour

Bromoethane and Chloroethane

The correct answer is option 3. Bromoethane and Chloroethane.

Bromoethane and chloroethane are both halogenated hydrocarbons, meaning they contain a hydrocarbon chain (ethane) with a halogen atom (bromine or chlorine) attached. These molecules have similar molecular structures and sizes, differing only in the type of halogen atom present.

Both bromoethane and chloroethane are polar molecules due to the electronegativity difference between the carbon and halogen atoms, resulting in a dipole moment. This polarity allows for dipole-dipole interactions between molecules.

In nearly ideal solutions, the interactions between solute and solvent molecules closely resemble those in the pure substances. Since bromoethane and chloroethane have similar molecular structures, sizes, and intermolecular forces (dipole-dipole interactions), their solution is expected to exhibit nearly ideal behavior.

In such solutions, there are minimal deviations from ideal behavior, and properties like vapor pressure, boiling point elevation, and osmotic pressure follow ideal solution behavior closely.

Therefore, the solution containing bromoethane and chloroethane is nearly ideal in behavior due to the similarities in their molecular structures and intermolecular forces. This makes option 3 the correct answer.