In a CO2 molecule, the chemical bond between carbon and oxygen is polar. This is because oxygen is more electronegative than carbon, resulting in an unequal sharing of electrons and creating a dipole moment. However, due to the linear geometry of the CO2 molecule, the two polar bonds are oriented in opposite directions, which causes their dipole moments to cancel each other out. As a result, the overall molecule is nonpolar, even though the individual carbon-oxygen bonds are polar.