Which of the following is true for $[Fe(CN)_6]^{3-}$ and $[FeF_6]^{3-}$?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The total number of geometrical isomers shown by $[Co(en)_2 Cl_2]^{+}$ complex ion is three.
Reason $R$: $[Co(en)_2 Cl_2]^{+}$ complex ion has an octahedral geometry.
In the light of the above statements,choose the most appropriate answer from the options given below:

The metal ions that have the calculated spin-only magnetic moment value of $4.9 \ B.M.$ are:
$A. Cr^{2+}$ $B. Fe^{2+}$ $C. Fe^{3+}$ $D. Co^{2+}$ $E. Mn^{3+}$
Choose the correct answer from the options given below:

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

Discuss the magnetic properties of coordination compounds.

The $d-$electron configurations of $Cr^{2+}, Mn^{2+}, Fe^{2+}$ and $Co^{2+}$ are $d^4, d^5, d^6$ and $d^7$ respectively. Which one of the following will exhibit minimum paramagnetic behaviour?
(At. nos. $Cr = 24, Mn = 25, Fe = 26, Co = 27$)