The total number of geometrical isomers possible for an octahedral complex of this type $\left[{\mathrm{MA}}_2{\mathrm{B}}_2{\mathrm{C}}_2\right]$ is 

(M = transition metal; A, B and C are monodentate ligands)

1.  3

2.  4

3.  5

4.  6

The IUPAC name of $\left[\mathrm{Co}\left(\mathrm{ONO}\right){\left({\mathrm{NH}}_3\right)}_5\right]{\mathrm{Cl}}_2$ is:

1. Pentamminenitro-O-cobalt(II)chloride

2. Pentamminenitroso-O-cobalt(III)chloride  

3. Pentaamminenitrito-O-cobalt(III) chloride

4. Pentammineoxo-nitrocobalt(III)chloride

The metal carbonyl which is paramagnetic is

1. $\mathrm{Ni}{\left(\mathrm{CO}\right)}_4$

2. $\mathrm{V}{\left(\mathrm{CO}\right)}_6$

3. $\mathrm{Cr}{\left(\mathrm{CO}\right)}_6$

4. $\mathrm{Fe}{\left(\mathrm{CO}\right)}_5$

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

How many isomers are possible for complex $\left[\mathrm{Co}{\left(\mathrm{ox}\right)}_2{\mathrm{Cl}}_2\right]+?$

1.  1

2.  3

3.  2

4.  4

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

Among the following complexes, the one that can exist as facial (fac) and meridional (mer) isomers is

1.  $\left[\mathrm{Co}{\left({\mathrm{NO}}_2\right)}_3{\left({\mathrm{NH}}_3\right)}_3\right]$

2.  ${\mathrm{K}}_3\left[\mathrm{Fe}{\left(\mathrm{CN}\right)}_6\right]$

3.  $\left[\mathrm{Co}{\left({\mathrm{H}}_2\mathrm{O}\right)}_2{\left({\mathrm{NH}}_3\right)}_4\right]{\mathrm{CI}}_3$

4.  $\left[\mathrm{CoCl}{\left({\mathrm{NH}}_3\right)}_5\right]\mathrm{CI}$  

 $$\begin{gathered} \mathrm{Among} \left(\mathrm{i}\right) {\left[\mathrm{Cr}{\left(\mathrm{en}\right)}_3\right]}^{3+}, \left(\mathrm{ii}\right) \mathrm{trans}-{\left[\mathrm{Cr}{\left(\mathrm{en}\right)}_2{\mathrm{Cl}}_2\right]}^{+}, \\ \left(\mathrm{iii}\right) \mathrm{cis}-{\left[\mathrm{Cr}{\left(\mathrm{en}\right)}_2{\mathrm{Cl}}_2\right]}^{+}, \left(\mathrm{iv}\right) {\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4\mathrm{Cl}\right]}^{+}, \mathrm{the} \mathrm{optically} \mathrm{active} \\ \mathrm{complexes} \mathrm{are} \end{gathered}$$

1.  (i) and (ii)

2.  (i) and (iii)

3.  (ii) and (iii)

4.  (ii) and (iv)