The geometry and magnetic properties of [NiCl₄]^2-, respectively, are : 

1. Tetrahedral, Paramagnetic

2. Tetrahedral, Diamagnetic

3. Square planar, Paramagnetic

4. Square planar, Diamagnetic  

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 compound that has the maximum coordination number is/are:

1. [Co(NH₃)₆]³⁺
2. [Cr(C₂O₄)₃]^3-
3. [CoCl₃(H₂O)₃]
4. All of the above have the same coordination number

The complex that can exhibit linkage isomerism is:

A person with osteoporosis is also experiencing lead poisoning, and ethylenediamine tetraacetic acid (EDTA) is prescribed for treatment. Which form of EDTA is most suitable for this administration?

1. EDTA

2. Tetrasodium salt

3. Disodium salt

4. Calcium dihydrogen salt

The complex that can exhibit optical activity among the following is:

1. [CoCl₆]^3-

2. [Co(en)CI₄]^-

3. cis-[Co(en)₂Cl₂]⁺

4. trans-[Co(en)₂Cl₂]⁺ 

The oxidation state of cobalt in the following molecule is:

1. 3

2. 1

3. 2

4. 0

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 most stable complex among the following species is:

1.  $\left[\mathrm{Fe}{\left(\mathrm{CO}\right)}_5\right]$

2.  $[\mathrm{Fe}{\left(\mathrm{CN}\right)}_6{]}^{3-}$

3.  $[\mathrm{Fe}{\left({\mathrm{C}}_2{\mathrm{O}}_4\right)}_3{]}^{3-}$

4.  $[\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6{]}^{3+}$