Concept:Bond polarity is determined by the electronegativity difference (\( \Delta \text{E.N.} \)) between the two bonded atoms. However, bonding in Hydrogen Halides acts slightly unusually due to their molecular nature.
Formula:$$ \Delta \text{E.N.} = 4.0 (\text{F}) - 2.1 (\text{H}) = 1.9 \approx 2.0 $$
Solution:- Generally, an electronegativity difference > 1.7 suggests an ionic bond.
- However, HF is a distinct exception. It exists as discrete molecules and is a gas at room temperature, which are characteristic properties of covalent compounds.
- Therefore, despite the large electronegativity difference, HF strictly forms a highly polar covalent bond (with significant ionic character, but primarily covalent).
Why other options are incorrect:It is not non-polar (as electrons are unequal). It is a sigma bond, not a pi bond. It forms via mutual sharing, not through the dative donation of a lone pair.
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.