$A$ metal complex of coordination number six having three different types of ligands $a$,$b$ and $c$ of composition $Ma_2b_2c_2$ can exist in several geometrical isomeric forms; the total number of such isomers is

An octahedral complex with molecular composition $M \cdot 5NH_3 \cdot Cl \cdot SO_4$ has two isomers,$A$ and $B$. The solution of $A$ gives a white precipitate with $AgNO_3$ solution and the solution of $B$ gives a white precipitate with $BaCl_2$ solution. The type of isomerism exhibited by the complex is

Consider the complexes:
$I$. $[Pd(NH_3)_2 ClBr]$
$II$. $[Pd(NH_3)_2 Cl_2]$
$III$. $[Pd(en) Cl_2]$
$IV$. $[Pd(en) ClBr]$
$V$. $[Pd(en)_2 Cl_2]$
(en = ethylenediamine)
The total number of geometrical isomers of $(I)$ is the same as the total number of geometrical isomers of:

The magnetic moment of $Fe^{2+}$ is $B.M$.

What is the reason for the deviation between the experimental and theoretical values of magnetic moment?

Which of the following would exhibit ionisation isomerism?