Which of the following complexes has a square planar geometry?

The $d$-electronic configuration of $[CoCl_4]^{2-}$ in a tetrahedral crystal field is $e^m t_2^n$. The sum of '$m$' and the number of unpaired electrons is $.............$.

Using valence bond theory,explain the following in relation to the complexes given below: $[Mn(CN)_{6}]^{3-}, [Co(NH_{3})_{6}]^{3+}, [Cr(H_{2}O)_{6}]^{3+}, [FeCl_{6}]^{4-}$
$(i)$ Type of hybridisation.
$(ii)$ Inner or outer orbital complex.
$(iii)$ Magnetic behaviour.
$(iv)$ Spin only magnetic moment value.

Which of the following statements is incorrect?

The structure of iron pentacarbonyl is:

Aluminium chloride in acidified aqueous solution forms an ion having which geometry?