Which metal ion is present in Vitamin- B₁₂?

1. Zinc

2. Calcium

3. Iron

4. Cobalt

Which of the following can show geometrical isomerism?

(a)             (b) $\left[\mathrm{Co}\right(\mathrm{en}{)}_2{\mathrm{NH}}_3\mathrm{Cl}{]}^{2+}$

(c) Both (a) and (b)                                (d) None of these 

How many isomers are possible for complex [Co(Ox)₂Cl₂]^3-?

1.  1

2.  3

3.  2

4.  4

Which one of the following reactions is correct?

1.  $\left[\mathrm{Fe}\right(\mathrm{CO}{)}_5]+2\mathrm{NO}\to \left[\mathrm{Fe}\right(\mathrm{CO}{)}_2\left(\mathrm{NO}{)}_2\right]+3\mathrm{CO}$

2.  $\left[\mathrm{Fe}\right(\mathrm{CO}{)}_5]+2\mathrm{NO}\to \left[\mathrm{Fe}\right(\mathrm{CO}{)}_3\left(\mathrm{NO}{)}_2\right]+2\mathrm{CO}$

3.  $\left[\mathrm{Fe}\right(\mathrm{CO}{)}_5]+3\mathrm{NO}\to \left[\mathrm{Fe}\right(\mathrm{CO}{)}_2\left(\mathrm{NO}{)}_3\right]+3\mathrm{CO}$

4. $\left[\mathrm{Fe}\right(\mathrm{CO}{)}_5]+3\mathrm{NO}\to \left[\mathrm{Fe}\right(\mathrm{CO}{)}_3\left(\mathrm{NO}{)}_3\right]+2\mathrm{CO}$

1. NO₃^- acts as a monodentate ligand.
2. The Ce atom has a coordination number of 12.
3. The shape of the complex ion is an icosahedron.
4. The solution is used as an oxidizing agent.

Which of the following metal carbonyl is paramagnetic in nature?

The IUPAC name of [Co(ONO)(NH₃)₅]Cl₂ is: 

1.  Pentamminenitrocobalt(II)chloride

2.  Pentamminenitrsoocobalt(III)chloride  

3. Pentaaminenitrito-O-cobalt(III)chloride.  

4. Pentammineoxo-nitrocobalt(III)chloride

The total number of geometrical isomers possible for an octahedral complex of $\left[{\mathrm{MA}}_2{\mathrm{B}}_2{\mathrm{C}}_2\right]$ are:
(M = transition metal; A, B and C are monodentate ligands)

Hybridization and geometry of ${\left[\mathrm{Ni}{\left(\mathrm{CN}\right)}_4\right]}^{2-}$ are

1.  $s{p}^{2}d$ and tetrahedral

2.  $s{p}^3$ and square planar

3.  $s{p}^3$ and tetrahedral

4.  $ds{p}^2$ and square planar