The spin magnetic moment of cobalt in $Hg[Co(SCN)_4]$ is

The theoretical value of the magnetic moment of the complex formed by the reaction of $Fe^{3+}$ ion with $CN^{-}$ ligand is .......... $B.M.$

Which of the following complex compounds exhibits cis-trans isomerism?

Number of stereoisomers possible for the octahedral complexes $[Co(NH_3)_3Cl_3]$ and $[Ni(en)_2Cl_2]$,respectively,are (where $en = 1,2-$ethylenediamine):

Given below are two statements:
Statement-$I$ : The number of paramagnetic species among $[CoF_6]^{3-}$, $[TiF_6]^{3-}$, $V_2O_5$ and $[Fe(CN)_6]^{3-}$ is $3$.
Statement-$II$ : $K_4[Fe(CN)_6] < K_3[Fe(CN)_6] < [Fe(H_2O)_6]SO_4 \cdot H_2O < [Fe(H_2O)_6]Cl_3$ is the correct order in terms of number of unpaired electron$(s)$ in the complexes.
In the light of the above statements, choose the correct answer from the options given below.

The number of geometrical isomers possible in triamminetrinitrocobalt $(III)$ is $X$ and in trioxalatochromate $(III)$ is $Y$. Then the value of $X+Y$ is $....$