Question

The standard molar enthalpy of vaporisation (\(\Delta_\text{vap} H^\circ\)) of A, B, and C liquids is 23.3, 41, and 29 kJ mol\(^{-1}\) respectively. The correct order of dipole-dipole attractive forces in these liquids is:

• A. B > C > A
• B. B > A > C
• C. A > C > B
• D. A > B > C

Hint:

Stronger dipole-dipole forces correspond to higher enthalpies of vaporisation in polar liquids.

Answer 1

The Correct Option is A

Step 1: Link vaporisation enthalpy to intermolecular forces.
Higher \(\Delta_{vap}H\) means stronger intermolecular (dipole-dipole) forces. Values: A = 23.3, C = 29, B = 41 kJ/mol.

Step 2: Rank.
B (41) \(>\) C (29) \(>\) A (23.3).
\[ \boxed{B > C > A} \]