$[Co(NH_3)_5SO_4]Br$ and $[Co(NH_3)_5Br]SO_4$ are a pair of isomers.

The species that can have a $trans$-isomer is: ($en = \text{ethane-}1,2\text{-diamine}$,$ox = \text{oxalate}$)

Correct increasing order of spin magnetic moment $($in $B.M.)$ for the following complexes is:
$(I) \ [FeF_6]^{3-} \ (II) \ [V(H_2O)_6]^{2+} \ (III) \ [Fe(H_2O)_6]^{2+}$

The pair in which both species have the same magnetic moment (spin-only value) is:

Which of the following compounds does not show optical activity?

Which of the following coordination compounds would exhibit optical isomerism?