A compound is made by mixing cobalt (III) nitrate and potassium nitrite solution in the ratio of 1 : 3. The aqueous solution of the compound showed 4 particles per molecule whereas molar conductivity reveals the presence of six electrical. charges. The formula of the compound is

1.  $\mathrm{Co}{\left({\mathrm{NO}}_2\right)}_3 · 2{\mathrm{KNO}}_2$

2.  $\mathrm{Co}{\left({\mathrm{NO}}_2\right)}_3 · 3{\mathrm{KNO}}_2$

3.  ${\mathrm{K}}_3\left[\mathrm{Co}{\left({\mathrm{NO}}_2\right)}_6\right]$

4.  $\mathrm{K}\left[\mathrm{Co}{\left({\mathrm{NO}}_2\right)}_4\right]$

0.001 mole of $[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5\left({\mathrm{NO}}_3\right) \left({\mathrm{SO}}_4\right)]$ was passed through a cation exchanger and the acid coming out of it required 20 ml of 0.1 M NaOH for neutralization. Hence, the complex is

1.  $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5{\mathrm{SO}}_4\right]{\mathrm{NO}}_3$

2.  $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5 N{O}_3\right]{\mathrm{SO}}_4$

3.  $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5{\mathrm{SO}}_4\right]{\mathrm{NO}}_3{\mathrm{SO}}_4$

4.  All of these

Which of the following statements is correct regarding the chirality (optical isomerism) of the cis and a trans isomer of the type $\mathrm{M}{\left(\mathrm{aa}\right)}_2{\mathrm{b}}_2$ (M stands for metal, aa is a bidentate ligand, and b is a chiral ligand)?

(1)  The trans form is achiral and optically inactive while the cis form is chiral and exists in two enantiomeric forms

(2)  Both cis and transforms are achiral and optically inactive

(3)  The transform is chiral and exists in two enantiomeric forms while the cis form is achiral and optically inactive

(4)  Both the cis and transform are chiral and each exists in two enantiomeric form

Which statement about the co-ordination number of a cation is true?

(1)  Metal ions exhibit only a single characteristic co-ordination number

(2)  The co-ordination number is equal to the number of ligands bonded to the metal atom

(3)  The co-ordination number is determined solely by the number of empty d-orbitals in the atom

(4)  Co-ordination number is equal to the number of coordinate bonds between the metal cation and ligands

If ${\mathrm{Cd}}^{2+}$ and ${\mathrm{Cu}}^{2+}$ both are present, both are complexed by ${\mathrm{CN}}^{-}$ and ${\mathrm{H}}_2\mathrm{S}$ gas is passed, which one of the following pairs of complexes and their relative stability enables the separation of ${\mathrm{Cu}}^{2+}$ and ${\mathrm{Cd}}^{2+}$?

1.  ${\mathrm{K}}_3\left[\mathrm{Cu}\left({\mathrm{CN}}_4\right)\right]$: more stable and ${\mathrm{K}}_2\left[\mathrm{Cd}\left({\mathrm{CN}}_4\right)\right]$: less stable

2.  ${\mathrm{K}}_2\left[\mathrm{Cu}\left({\mathrm{CN}}_4\right)\right]$: less stable and ${\mathrm{K}}_2\left[\mathrm{Cd}\left({\mathrm{CN}}_4\right)\right]$: more stable

3.  ${\mathrm{K}}_2\left[\mathrm{Cu}\left({\mathrm{CN}}_4\right)\right]$: more stable and ${\mathrm{K}}_2\left[\mathrm{Cd}\left({\mathrm{CN}}_4\right)\right]$: more stable

4.  ${\mathrm{K}}_3\left[\mathrm{Cu}\left({\mathrm{CN}}_4\right)\right]$: less stable and ${\mathrm{K}}_2\left[\mathrm{Cd}\left({\mathrm{CN}}_4\right)\right]$: more stable

The spin-only magnetic moments of ${\left[\mathrm{Mn}{\left(\mathrm{CN}\right)}_6\right]}^{4-} \mathrm{and} {\left[{\mathrm{MnBr}}_4\right]}^{2-}$ in Bohr Magnetons, respectively, are

1.  5.92 and 5.92

2.  4.89 and 1.73

3.  1.73 and 5.92

4.  1.73 and 1.73

The crystal field stabilization energies (CFSE) of high spin and low spin $d^6$ metal complexes in terms of ${∆}_0$, respectively are

1.  -0.4 and -2.4

2.  -2.4 and -0.4

3.  -0.4 and 0.0

4.  -2.4 and 0.0

The oxidation state of cobalt in the following molecule is 

1.  3

2.  1

3.  2

4.  0

For a tetrahedral complex [MCl₄]^2-, the spin-only magnetic moment is 3.83 B.M. The element M is:

1. Co

2. Cu

3. Mn

4. Fe

Among the following, the species that is both tetrahedral and diamagnetic is

1.  ${\left[{\mathrm{NiCl}}_4\right]}^{2-}$

2.  ${\left[\mathrm{Ni}{\left(\mathrm{CN}\right)}_4\right]}^{2-}$

3.  $\left[\mathrm{Ni}{\left(\mathrm{CO}\right)}_4\right]$

4.  ${\left[\mathrm{Ni}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{2+}$