Which of the Following Molecules Contains the Most Polar Covalent

Question

Which of the following molecules contains the most polar covalent bond?
A)H₂
B)O₂
C)CO₂
D)H₂O
E)CH₄

Accepted Answer

H₂ has a nonpolar covalent bond because the electronegativity difference between the two atoms is zero. O₂ has a nonpolar covalent bond because the electronegativity difference between the two atoms is also zero. CO₂ has a polar covalent bond, but it is symmetrical, so the polarities cancel out, resulting in a nonpolar molecule. H₂O has a polar covalent bond due to the difference in electronegativity between hydrogen and oxygen. The electronegativity difference creates partial positive and negative charges on the hydrogen and oxygen atoms, resulting in a polar molecule. CH₄ has a nonpolar covalent bond because the electronegativity difference between carbon and hydrogen is small enough that the molecule is considered nonpolar.