Which of the following outer octahedral complexes have the same number of unpaired electrons?
$1$. $[MnCl_6]^{3-}$
$2$. $[FeF_6]^{3-}$
$3$. $[CoF_6]^{3-}$
$4$. $[Ni(NH_3)_6]^{2+}$

Select the correct code of $TRUE$ and $FALSE$ for the given statements:
$(a)$ Peroxide ion as well as dioxygen molecule both are paramagnetic species.
$(b)$ In the set of isomers,$[Cr(H_2O)_6]Cl_3$ and $[CrCl(H_2O)_5]Cl_2 \cdot H_2O$,both compounds can easily lose water molecules on treatment with conc. $H_2SO_4$.
$(c)$ During the transformation $NO \to NO^+$,bond length decreases and magnetic behavior changes from paramagnetic to diamagnetic.
$(d)$ An ether is more volatile than an alcohol,both having the same molecular formula.

Which of the following pairs of isomers and their types of isomerism are correctly matched?
$1.$ $[Co(NH_3)_5NO_2]Cl_2$ and $[Co(NH_3)_5ONO]Cl_2$ $-$ Linkage
$2.$ $[Cu(NH_3)_4] [PtCl_4]$ and $[Pt(NH_3)_4] [CuCl_4]$ $-$ Coordination
$3.$ $[Pt(NH_3)_4Cl_2]Br_2$ and $[Pt(NH_3)_4Br_2]Cl_2$ $-$ Ionization

Which of the following pairs of isomers and their types of isomerism are correct? Select the correct option.
$(1)\ [Co(NH_3)_5(NO_2)]Cl_2$ and $[Co(NH_3)_5(ONO)]Cl_2$: Linkage isomerism
$(2)\ [Cu(NH_3)_4][PtCl_4]$ and $[Pt(NH_3)_4][CuCl_4]$: Coordination isomerism
$(3)\ [Pt(NH_3)_4Cl_2]Br_2$ and $[Pt(NH_3)_4Br_2]Cl_2$: Ionization isomerism

Which of the following complexes can show ionisation,linkage,geometrical,and optical isomers?

The number of geometrical isomers of a planar complex $M_{abcd}$ is