Which of the following molecules is **non-polar** (has zero permanent dipole moment)?
- H₂O
- NH₃
- HCl
- CO₂
Show answer and solution
Correct answer: D. CO₂
CO₂ is linear (O=C=O)
the two C=O bond dipoles cancel by symmetry, so net $\vec p = 0$.
HCl, H₂O (bent, ~105°) and NH₃ are polar with permanent dipole moments and behave as polar dielectrics.