Which of the following complexes exhibits both geometric and optical isomerism?

The magnetic moment of the complex anion $[Cr(NO)(NH_3)(CN)_4]^{2-}$ is $..........$ $B.M.$

Amongst $FeCl_{3} \cdot 3H_{2}O$,$K_{3}[Fe(CN)_{6}]$ and $[Co(NH_{3})_{6}]Cl_{3}$,the spin-only magnetic moment value of the inner-orbital complex that absorbs light at the shortest wavelength is $B.M.$ [nearest integer].

Among the species given below,the total number of diamagnetic species is. . . . . $H$ atom,$NO_2$ monomer,$O_2^{-}$ (superoxide),dimeric sulphur in vapour phase,$Mn_3O_4$,$(NH_4)_2[FeCl_4]$,$(NH_4)_2[NiCl_4]$,$K_2MnO_4$,$K_2CrO_4$

In which of the following ions is the spin-only magnetic moment the lowest?

Which of the following complexes exhibits optical activity?