Q2 ans A
(I have doubt in S2 only please explain. It by VBT AND CFT)
There are 6 NO2- . That gives Cobalt a +2 charge.
Cobalt is originally 4s2 3d7.
It then becomes 3d7.
Since NO2- is a strong field ligand, electrons would pair up in t2g orbitals; and the remaining electron would jump into higher orbitals to make room for ligand electrons.
That makes the hybridization d2sp3 possible and hence it is octahedral low spin complex. Also due to that one unpaired electron,it is now paramagnetic.
All 4s and 4p will go for hybridisation
That means that unpaired electron will jump in 5th orbital?
We don't know that exactly, whether it will jump into 4d or 5s.
(Exceptions to the n+l rule exist at higher atomic numbers)