In: Chemistry
a.
There are 3 possible isomers of AX3, with 2 lone pairs & 3 single bond, are shown. According to Vesper theory the 3rd arrangement is proper, as in that arrangement molecule feels least repulsion. & its polar in nature shown in the photo.
While in case A atom with 3 lone pair 3 single bond 2 isomer shown below,
The 1st one with T shape is more stabel, stable less repulsion
b. The hybrid orbitals = number of lone pairs + number of bond pairs. As in the 2nd case the central atom A with 3 lone pairs & 3 bond pairs.Then the hybrid orbitals - 6 then the hybridization is sp3d2.
Due Paramagnetic behaviour, molecule attract by an external magnetic field. Hybridization don't play a good role at predicting if a molecule is paramagnetic or diamagnetic. For a molecule to be a paramagnetic need to have overall magnetic momentum of the molecule. That's means at least 1 unpaired electron present in the molecule.
as you can see all electrons are paired in oxygen molecule that's why VBT( valence bond theory, explain the formation of bond by sharing unpired electron of two atom forming a orbital by overlaping of hybrid orbital) explain that oxygen is diamagnetic.