Hydrogen bonding plays a central role in which of the following phenomena?

Options

A. Ice floats in water
B. Higher Lewis basicitiy of primary amines than tertiary amines in aqueous solutions
C. forminc acid is more acidic than acetic acid
D. Dimerisation of acetic acid in benzene

Answer

A, B, D

Explanation

Due to cage like structure in which each water molecule is surrounded by four other water molecules tetrahedrally through H-bonding, there are a number of vacant spaces I the crystal lattice of ice. As a result, ice has lower density than water and hence floats in water.
(b) Due to greater H-bonding, the ammonium cation derived from `1^(@)` amine is mroe stable than that derived from `3^(@)` amine. (c) Due to absence of +I-effect of the `CH_(3)` group, HCOOH is a stronger acid than `CH_(3)COOH` and not due to H-bonding. thus. option (c) is wrong.
(d) Acetic aacid dimerises in benzene due to H-bonding.