Final answer:
Molecules such as CO2 (carbon dioxide), BH3 (boron trihydride), and CF4 (carbon tetrafluoride) have no overall molecular dipole moment due to the symmetrical arrangement of atoms and the cancellation of individual bond dipoles.
Step-by-step explanation:
To determine which of the specified compounds do not have an overall molecular dipole moment, we must consider their molecular geometry and the electronegativity differences between the bonded atoms. A molecule with symmetrical geometry and polar bonds might still have no net dipole moment if the individual bond dipoles cancel out.
For CO2 (carbon dioxide), the molecule is linear with oxygen atoms at each end, which means the dipoles from the C=O bonds point in opposite directions and cancel each other out, resulting in no net dipole moment.
BH3 (boron trihydride) is another example. It is a planar molecule with a trigonal planar geometry, and the dipoles from the B-H bonds cancel due to the molecule's symmetry, resulting in no net dipole moment.
CF4 (carbon tetrafluoride) has a tetrahedral geometry with fluorine atoms symmetrically arranged around the carbon atom. The symmetry leads to the cancellation of dipole moments, so CF4 has no overall dipole moment either.