(1) If AB4 molecule is a square pyramidal then it has one lone pair and their structure should be
and it should be polar because dipole moment of lone pair of 'A' never be cancelled by others.
(2) If AB4 molecule is a tetrahedral then it has no lone pair and their structure should be
and it should be non polar due to perfect symmetry.
(3) If AB4 molecule is a rectangular planar then
it should be non-polar because the vector sum of dipole moment is zero.
(4) If AB4 molecule is a square planar then
it should be non-polar because the vector sum of the dipole moment is zero.
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