Concept:Hydrogen bonding requires a hydrogen atom covalently bonded to a highly electronegative atom (N, O, or F).
Formula:Not applicable.
Solution:- \( \text{H}_2\text{O} \), \( \text{HF} \), and \( \text{NH}_3 \) all feature hydrogen covalently bonded to small, highly electronegative atoms, leaving the hydrogen intensely electron-deficient and capable of forming H-bonds.
- In Methane (\( \text{CH}_4 \)), carbon and hydrogen have very similar electronegativities (2.5 and 2.1, respectively).
- Because the bond is essentially non-polar, the hydrogen atoms do not carry a significant partial positive charge, meaning hydrogen bonding is entirely absent. Methane relies only on London dispersion forces.
Why other options are incorrect:Water, hydrogen fluoride, and ammonia are the three classic textbook examples of molecules that strongly exhibit hydrogen bonding.
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.