Final answer:
Among the given options, NO₂ (nitrogen dioxide) is the molecule with a net dipole moment due to its bent geometry and unsymmetrical charge distribution.
Step-by-step explanation:
To determine which molecule has a net dipole moment, we evaluate the molecular geometry and electronegativity differences between the atoms involved. A molecule like CH4 (methane) is nonpolar because it is tetrahedral and symmetrical, leading to the cancellation of any bond dipoles. Similarly, N2 is nonpolar because it is a diatomic molecule with two identical atoms sharing electrons equally, resulting in no dipole moment.
CCl4 (carbon tetrachloride) is also nonpolar because of its symmetrical tetrahedral structure, causing the bond dipoles to cancel out. The geometry of BF3 is trigonal planar, and even though the bonds are polar, the symmetry leads to overall cancellation of dipole moments, resulting in no net dipole.
However, NO2 (nitrogen dioxide) has a bent structure due to the presence of a lone pair on the nitrogen, leading to an unsymmetrical distribution of charge and, consequently, a net dipole moment, making it a polar molecule.