Find the paramagnetic compound containing two unpaired electrons.

1. K₃[Fe(CN)₆]

2. K₂[NiCl₄]

3. K₂[CoCl₄]

4. Na₂[Ni(CN)₄]

Which of the following species can act as an oxidising agent?

1. $\left[\mathrm{Cr}{\left(\mathrm{CO}\right)}_6\right]$

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

3. $[\mathrm{Mn}{\left(\mathrm{CO}\right)}_6{]}^{+}$

4. $\left[\mathrm{V}{\left(\mathrm{CO}\right)}_6\right]$

The geometry and magnetic behaviour of the complex [Ni(CO)₄] respectively are:

1. Square planar and diamagnetic.

2. Tetrahedral and diamagnetic.

3. Square planar and paramagnetic.

4. Tetrahedral and paramagnetic.

Number of possible isomers for the complex [Co(en)₂Cl₂]Cl will be:
(en=ethylenediamine) 

The IUPAC name for complex ion, [Fe(CN)₆]^3- is:

A paramagnetic ion among the following, forms an outer orbital complex is:

1. $\left[Ni\right(N{H}_3{)}_6{]}^{2+}$

2. $\left[Zn\right(N{H}_3{)}_6{]}^{2+}$

3. $\left[Cr\right(N{H}_3{)}_6{]}^{3+}$

4. $\left[Co\right(N{H}_3{)}_6{]}^{3+}$

Which among the following is a diamagnetic complex?

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

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

3. ${\left[{\mathrm{CoF}}_6\right]}^{3-}$

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

The complex ion among the following that cannot absorb visible light is:

1. [Ni(CN)₄]^2-

2. [Cr(NH₃)₆]³⁺

3. [Fe(H₂O)₆]²⁺

4. [Ni(H₂O)₆]²⁺

The existence of two different coloured complexes with the composition of [Co(NH₃)₄Cl₂]⁺  is due to: