Concept:The presence or absence of a lone pair on the central atom dictates whether a triatomic molecule is linear (non-polar) or bent (polar).
Formula:$$ \text{CO}_2 = \text{AB}_2 \quad ; \quad \text{SO}_2 = \text{AB}_2\text{E} $$
Solution:- In \( \text{CO}_2 \), Carbon has 0 lone pairs. The two double bonds repel each other equally to a 180° angle, making the molecule perfectly linear. The opposing dipoles cancel out, making it non-polar.
- In \( \text{SO}_2 \), Sulfur has 1 lone pair. This lone pair repels the two double bonds, bending the molecule into an angular (V) shape. Because it is asymmetrical, the dipoles do not cancel, making it polar.
Why other options are incorrect:- Option A, Option B, Option D: These options fail to recognize the structural difference caused by Sulfur's lone pair compared to Carbon's empty valence shell.
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.