Final answer:
H₂O (water) is a polar molecule, while CO₂ (carbon dioxide) is nonpolar.
Step-by-step explanation:
A molecule is considered polar if it has a separation of positive and negative charges due to an uneven distribution of electron density. From the given options, the molecule H₂O (water) is polar. Water has a bent molecular geometry and the oxygen atom pulls electrons more strongly than the hydrogen atoms, creating a partial negative charge on the oxygen and partial positive charges on the hydrogens.
In contrast, CO₂ (carbon dioxide) is nonpolar. CO₂ has a linear molecular geometry, and although the carbon-oxygen bonds are polar, the overall molecule is symmetric, resulting in the cancellation of the dipole moments and no net overall charge separation.