Chemistry

Question Analysis
This question involves molecular polarity. The main focus is on determining which molecule has no net dipole moment, making it nonpolar.

Key Concept Explanation
Molecular polarity depends on the polarity of individual bonds, and the molecular geometry (symmetry).

Step-by-step Solution
1. Analyze each molecule:
NO₂: Polar N=O bonds + bent asymmetric structure → polar molecule. 
SO₂: Polar S=O bonds + bent asymmetric structure → polar molecule. 
SO₃: Polar S=O bonds + trigonal planar symmetrical structure → dipole moments cancel out → nonpolar molecule. Correct.
NH₃: Polar N-H bonds + trigonal pyramidal asymmetric structure → pol...