Which statement about the coordination number of a cation is true?

1.	Metal ions exhibit only a single characteristic co-ordination number.
2.	The coordination number is equal to the number of ligands bonded to the metal atom.
3.	The coordination number is determined solely by the number of empty d-orbitals in the atom
4.	Coordination 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 (d⁶) octahedral metal complexes in terms of Δ₀, 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 ${\left[{\mathrm{MCI}}_4\right]}^{2-}$, the spin-only magnetic moment is 3.83 B.M. The element M is 

1.  Co

2.  Cu

3.  Mn

4.  Fe

Tetrahedral and diamagnetic compound among the following is:

The number of ions produced in water by the dissolution of the complex having the empirical formula [Co(NH₃)₄Cl₂]CI is: 

1.  1

2.  2

3.  4

4.  3

Spin-only magnetic moments of [Fe(NH₃)₆]³⁺ and [FeF₆]^3-  in BM are, respectively :

In an aqueous solution, ${\left[\mathrm{Co}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{2+}$ (X) reacts with molecular oxygen in the presence of excess liquor $N{H}_3$ to give a new complex Y. The number of unpaired electrons in X and Y are, respectively

1. 3, 1

2. 3, 0

3. 3, 3

4. 7, 0