Match the complex ions give in Column I with the colours given in column II and assign the correct code.

Column I             (Complex ion)	Column II               (Colour)
A. $[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_6{]}^{3+}$	1. Violet
B. $\left[\mathrm{Ti}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right){]}^{3+}$	2. Green
C. ${\left[\mathrm{Ni}({\mathrm{H}}_2{\mathrm{O}}_6\right]}^{2+}$	3. Pale blue
D. ${\left[\mathrm{Ni}{\left({\mathrm{H}}_2\mathrm{O}\right)}_4\left(\mathrm{en}\right)\right]}^{2+}$	4. Yellowish orange

Codes:

Options:	A	B	C	D
1.	2	3	4	1
2.	3	1	5	2
3.	5	4	3	2
4.	4	3	2	1

IUPAC name of ${\mathrm{H}}_2\left[{\mathrm{PtCl}}_6\right]$ is:

1. hydrogen hexachloroplatinate (IV)

2. dihydrogen hexachloroplatinate (IV)

3. hydrogen hexachloroplatinic (IV) acid

4. hexachloroplatinic (IV) acid

Which of the following complexes is not expected to exhibit isomerism?

Given the following pair of isomers:
[Cr(NH₃)₆][Cr(NO₂)₆] and
[Cr(NH₃)₄(NO₂)₂][Cr(NH₃)₂(NO₂)₄]
Aside from X-ray diffraction, how could the following pairs of isomers be distinguished from one another?

1. Cryoscopic method
2. Measuring their molar conductance
3. Measuring their magnetic moments
4. Observing their colors

For the complexes [Co(NH₃)₆]Cl₃ and [Co(NH₃)₆]Cl₂​, identify the correct matching property from the given options.

What are the geometries of \([Ni(CO)_4]\) and \([Ni(PPh_3)_2Cl_2]\) respectively?

1. Both square planar.

2. Tetrahedral and square planar, respectively.

3. Both tetrahedral.

4. Square planar and tetrahedral, respectively.