Final answer:
Molecules XeF₄ and CCl₄ are nonpolar due to their symmetrical geometries which cancel bond polarities, whereas NH₃, CH₃Br, and GaH₃ are polar due to their asymmetrical shapes and net dipole moments.
Step-by-step explanation:
To predict whether the given molecules XeF₄, NH₃, CH₃Br, CCl₄, CF₄, and GaH₃ are polar or nonpolar, we must consider the electron pair geometry and molecular structure which involve chemical bonding and molecular geometry.
- XeF₄: XeF₄ is a nonpolar molecule due to its square planar geometry which cancels out polar bonds symmetrically.
- NH₃: NH₃ (ammonia) is a polar molecule with a trigonal pyramidal shape and a net dipole moment.
- CH₃Br: CH₃Br (methyl bromide) is polar because of the presence of a single polar C-Br bond and the overall asymmetry of the molecule.
- CCl₄: CCl₄ (carbon tetrachloride) is nonpolar because it has a symmetrical tetrahedral structure that cancels out individual bond polarities.
- CF₄: CF₄ (carbon tetrafluoride) is nonpolar as it also has a symmetrical tetrahedral structure similar to CCl₄, which cancels out the bond polarities.
- GaH₃: GaH₃ (gallane) is polar due to its trigonal planar structure and the net dipole as hydrogen atoms are less electronegative than gallium.