Concept: The strength of hydrogen bonding depends on the electronegativity of the atom to which hydrogen is bonded, and the size of the atom. Stronger hydrogen bonds are formed when hydrogen is bonded to highly electronegative and small atoms like F, O, or N. The more electronegative the atom, the more polarized the H-X bond, leading to a stronger partial positive charge on hydrogen and a stronger attraction to the lone pair of an adjacent electronegative atom.

Why (B) is correct:

• Hydrogen bonding in water (${\mathrm{H}}_2\mathrm{O}$) is stronger than in hydrogen peroxide (${\mathrm{H}}_2{\mathrm{O}}_2$).
• In ${\mathrm{H}}_2\mathrm{O}$, each oxygen atom is bonded to two hydrogen atoms and has two lone pairs. This allows for extensive and strong intermolecular hydrogen bonding.
• In ${\mathrm{H}}_2{\mathrm{O}}_2$, the oxygen atoms are bonded to each other (O-O bond) and each to one hydrogen atom. While hydrogen bonding does occur, the presence of the O-O single bond and the slightly different geometry (non-planar) can lead to less efficient packing and potentially weaker overall intermolecular H-bonding compared to water, where the H-bonds are more directional and extensive. Also, the electronegativity difference between O and H is the primary factor. The O-H bond in water is more polar than in H2O2 due to the inductive effect of the second oxygen in H2O2 slightly reducing the electron density on the first oxygen.

Option Analysis:

• A) $\mathrm{HF}<{\mathrm{NH}}_3$: Incorrect. HF forms much stronger hydrogen bonds than $\mathrm{N}{\mathrm{H}}_3$ because F is more electronegative than N, leading to a more polarized H-F bond.
• C) ${\mathrm{H}}_2{\mathrm{O}}_2>{\mathrm{H}}_2\mathrm{O}$: Incorrect. As explained above, ${\mathrm{H}}_2\mathrm{O}$ forms stronger hydrogen bonds than ${\mathrm{H}}_2{\mathrm{O}}_2$.
• D) ${\mathrm{NH}}_3>{\mathrm{H}}_2\mathrm{O}$: Incorrect. ${\mathrm{H}}_2\mathrm{O}$ forms stronger hydrogen bonds than $\mathrm{N}{\mathrm{H}}_3$ because O is more electronegative than N, leading to a more polarized O-H bond.

Correct Answer: (B)