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]

The octahedral complex that will not show geometrical isomerism is: 
 (A and B are monodentate ligands)

The number of unpaired electrons in the complex ion [CoF₆]^3– is:

(Atomic No. Co = 27)

1. 2

2. 3

3. 4

4. Zero

According to IUPAC nomenclature, sodium nitroprusside is named as:

1. Sodium nitro ferricyanide

2. Sodium nitro ferrocyanide

3. Sodium pentacyanidonitrosyl ferrate(II)

4. Sodium pentacyanonitrosyl ferrate(III)

The coordination compound that gives the maximum number of isomers is:

1. [Co(NH₃)₄Cl₂]

2. [Ni(en)(NH₃)₄]²⁺

3. [Ni(C₂O₄)(en)₂]

4. [Cr(SCN)₂(NH₃)₄]⁺

The hypothetical complex
chlorodiaquatriamminecobalt(III) chloride can be
represented as:

1. $\left[\mathrm{CoCl}{\left({\mathrm{NH}}_3\right)}_3{\left({\mathrm{H}}_2\mathrm{O}\right)}_2\right]{\mathrm{Cl}}_2$

2. $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_3\left({\mathrm{H}}_2\mathrm{O}\right){\mathrm{Cl}}_3\right]$

3. $\left[\mathrm{Co}{\left({\mathrm{NH}}_2\right)}_3{\left({\mathrm{H}}_2\mathrm{O}\right)}_2\mathrm{Cl}\right]$

4. $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_3{\left({\mathrm{H}}_2\mathrm{O}\right)}_3{\mathrm{Cl}}_3\right]$