Final answer:
Carbon monoxide (CO) is a polar molecule with a dipole moment pointing from carbon (C) (δ+) to the more electronegative oxygen (O) (δ-). However, carbon dioxide (CO₂) is nonpolar because its linear shape causes the two bond dipoles to cancel out.
Step-by-step explanation:
To determine the polar molecule and indicate the positive and negative ends of the dipole moment in CO, we look at the electronegativity of the atoms. Carbon (C) is less electronegative than oxygen (O), which means that the shared electrons are closer to the oxygen atom. This gives the oxygen a partial negative charge (δ-) and the carbon a partial positive charge (δ+). Since there is an uneven distribution of electron density, CO is a polar molecule with a dipole moment pointing from carbon to oxygen.
In the case of CO2, each carbon-oxygen (C=O) bond has a polar covalent bond, but they are arranged linearly and point in opposite directions. This arrangement leads to the cancellation of the bond dipole moments, resulting in CO2 being a nonpolar molecule with no overall dipole moment.