Question

Dimerisation of solute molecules in low dielectric constant solvent is due to :

• A. Hydrogen bond
• B. Covalent bond
• C. Co-ordinate bond
• D. Ionic bond

Answer 1

The Correct Option is A

Dimerisation of solute molecules in solvents with a low dielectric constant occurs predominantly due to hydrogen bonding.

Detailed Explanation: 

• (A) Hydrogen bond: Correct Answer. In solvents with low dielectric constants, intermolecular hydrogen bonds become stronger due to the reduced solvent polarity, leading to the formation of stable dimers. This phenomenon is typical in carboxylic acids (e.g., acetic acid dimerisation in benzene).
• (B) Covalent bond: Incorrect. Covalent bonds involve electron sharing within molecules, not between distinct molecules in solution under these conditions.
• (C) Co-ordinate bond: Incorrect. Coordinate bonds involve electron donation from one species to another, usually seen in complex formation, not typical for dimerisation in low dielectric solvents.
• (D) Ionic bond: Incorrect. Ionic bonds generally require solvents with high dielectric constants (like water) for ion stabilization and dissociation. They are not favored in solvents with low dielectric constants.

Conclusion:

The correct answer is Option (A): Hydrogen bond.