Chemical Bonding and Molecular Structure Part 1

(1) If AB4 molecule is a square pyramidal then it has one lone pair and their structure should beand 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 square planar thenit should be non polar because vector sum of dipole moment is zero.
(4) If AB4 molecule is a rectangular planar thenit should be non polar because vector sum of dipole moment is zero.