How many isomeric forms will the complex ion $[Co(NH_3)_4Cl_2]^+$ exhibit?

Explain why $[Fe(H_{2}O)_{6}]^{3+}$ has a magnetic moment value of $5.92 \ BM$ whereas $[Fe(CN)_{6}]^{3-}$ has a value of only $1.74 \ BM$.

Draw the structures of the geometrical isomers of $[Fe(NH_3)_2(CN)_4]^-$.

Identify the diamagnetic octahedral complex ions from below $:$
$A. [Mn(CN)_6]^{3-}$
$B. [Co(NH_3)_6]^{3+}$
$C. [Fe(CN)_6]^{4-}$
$D. [Co(H_2O)_3F_3]$
Choose the correct answer from the options given below $:$

Arrange the following coordination compounds in the increasing order of magnetic moments. (Atomic numbers: $Mn = 25$; $Fe = 26$)
$(A)$ $[FeF_{6}]^{3-}$
$(B)$ $[Fe(CN)_{6}]^{3-}$
$(C)$ $[MnCl_{6}]^{3-}$ (high spin)
$(D)$ $[Mn(CN)_{6}]^{3-}$

Which of the following coordination compounds exhibit both optical and geometrical isomerism?
$a$. $[Co(en)_2Cl_2]Br$
$b$. $[Pt(NH_3)_2Cl_2Br_2]$
$c$. $[Co(en)_3]Cl_3$
$d$. $[Pt(NH_3)_4Cl_2]$
$e$. $[Pt(NH_3)_2Cl_2]$