A metal ion present in vitamin B₁₂ is:

1.	Fe(II)	2.	Co(III)
3.	Zn(II)	4.	Ca(II)

The coordination number of Ni in ${\left[\mathrm{Ni}\right({\mathrm{C}}_2{\mathrm{O}}_4{)}_3]}^{4-}$ is:

The organometallic compound that is σ and $\mathrm{\pi }$ bonded is:

1. $\left[Fe{({\eta }^5-C_5{H}_5)}_2\right]$

2. $K\left[PtC{l}_3\right({\eta }^2-C_2{H}_4\left)\right]$

3. ${\left[Co{\left(CO\right)}_{5}N{H}_3\right]}^{+2}$

4. $Fe{\left(C{H}_3\right)}_3$

The incorrect option among the following is:

1. Ni(CO)₄, Tetrahedral, paramagnetic
2. [Ni(CN)₄]^2-, Square planar, diamagnetic
3. Ni(CO)₄, Tetrahedral, diamagnetic
4. [Ni(Cl)₄]2-, Tetrahedral, paramagnetic

The complex that will exhibit maximum ionic conductivity in aqueous solution is:

1. K₄[Fe(CN)₆]

2. [Co(NH₃)₆]Cl₃

3. [Cu(NH₃)₄]Cl₂

4. [Ni(CO)₄]

${\mathrm{FeSO}}_4$ solution mixed with ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4$ solution in 1:1 molar ratio gives the test of Fe²⁺ ion

but ${\text{CuSO}}_4$ solution mixed with aqueous ammonia in 1:4 molar ratio does not give the test of Cu²⁺ ion because:

The oxidation number and coordination number of Co in $\left[\mathrm{Co}\right({\mathrm{H}}_2\mathrm{O}\left)\right(\mathrm{CN}){\left(\mathrm{en}\right)}_2{]}^{2+}$respectively are -     

1.) 3, 6

2.) 3, 2

3.) 2, 2

4.) 1, 3

Total number of optical isomers [Pt(NH₃)(Br)(Cl)(py)] can show:

1. 3

2. 2

3. 1

4. 0

The difference between a weak field ligand and a strong field ligand is:

The crystal field splitting energy is: