Which of the following molecules has a non-zero net dipole moment (is polar)?
Answer and explanation
Correct answer: A. Water (H2O)
- Step 1: Water has two bonding pairs and two lone pairs on oxygen, giving a bent shape (bond angle ~104.5 degrees). Step 2. The individual polar O-H bond dipoles add vectorially to yield a permanent net molecular dipole moment. Answer: Water (H2O). Why not the others: In linear CO2, trigonal planar BF3, and tetrahedral CH4, symmetry causes bond dipoles to sum vectorially to zero.
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