Concept:A molecule's net dipole moment is the vector sum of its individual bond dipoles. If the molecule is perfectly symmetrical, these vectors cancel out.
Formula:$$ \text{O} = \text{C} = \text{O} \quad (180^{\circ}) $$
Solution:- Carbon dioxide (\( \text{CO}_2 \)) is an \( \text{AB}_2 \) type molecule with no lone pairs on the central Carbon atom.
- This gives it a perfectly linear geometry.
- The two highly electronegative Oxygen atoms pull electron density equally in exactly opposite directions, causing the bond dipole vectors to sum to zero.
Why other options are incorrect:- Option A & Option D: These geometries are asymmetrical and would result in a net polar molecule.
- Option C: Being triatomic does not guarantee a zero dipole (e.g., \( \text{H}_2\text{O} \) is triatomic and highly polar).
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.