Final answer:
Among the molecules SF₆, PCl₅, NH₄⁺, and H₂S, the molecule with a net dipole moment is H₂S due to its bent molecular geometry that prevents bond dipoles from cancelling out.
Step-by-step explanation:
The student's question is which molecule has a net dipole moment from the options SF6, PCl5, NH4+, and H2S. To determine a net dipole moment, we have to consider the molecular geometry and distribution of bond dipoles within the molecule. High-symmetry geometries like that seen in SF6 (octahedral) and PCl5 (trigonal bipyramidal) result in a nonpolar molecule because the bond dipoles cancel each other out. The NH4+ ion (ammonium) has a tetrahedral geometry with identical bonds, also leading to no net dipole. However, H2S has a bent molecular geometry with two bonding pairs and two lone pairs, leading to bond dipoles that do not cancel each other out, resulting in a molecule with a net dipole moment.