Concept:Hydrogen bonding requires a hydrogen atom covalently bonded to a small, highly electronegative atom, specifically Fluorine (F), Oxygen (O), or Nitrogen (N).
Formula:Not applicable.
Solution:- Ammonia (\( \text{NH}_3 \)) contains a Nitrogen atom bonded to Hydrogen. Nitrogen is sufficiently small and electronegative to pull electron density away from hydrogen, leaving it heavily partially positive.
- This allows the hydrogen to strongly attract the lone pair on the Nitrogen of a neighboring \( \text{NH}_3 \) molecule.
Why other options are incorrect:Sulfur (in \( \text{H}_2\text{S} \)), Iodine (in \( \text{HI} \)), and Silicon (in \( \text{SiH}_4 \)) are larger and less electronegative; therefore, their primary intermolecular forces are dipole-dipole interactions or London dispersion forces, not hydrogen bonds.
Quality & Fidelity Assurance:
Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.