Question

Given.$CrC{l_3}.6{H_2}O$ exists in different isomeric forms which slow different colours like violet and green. This is due to:
A. ionisation isomerism
B. coordination isomerism
C. optical isomerism
D. hydrate isomerism

Answer 1

In order to this question, to know the term by which $CrC{l_3}.6{H_2}O$ exists in different isomeric forms which slow different colours like violet and green, we should go through the different optional type of isomerism.

Complete step by step answer:
Water molecules are exchanged inside and outside the coordination sphere. The number of water molecules is different inside and outside the coordination sphere. These are called hydrate isomers.
(i). $[Cr{({H_2}O)_6}]C{l_3}$ has six water molecules inside the coordination sphere and zero water molecules outside the coordination sphere. It is violet in colour.
(ii). $[Cr{({H_2}O)_5}Cl]C{l_2}.{H_2}O$ has five water molecules inside the coordination sphere and one water molecule outside the coordination sphere. It has a blue-green colour.
(iii). $[Cr{({H_2}O)_4}C{l_2}]Cl.{H_2}O$ has four water molecules inside the coordination sphere and two water molecules outside the coordination sphere, it has a green colour.

So, the correct answer is Option D.

Note: Hydrate isomerism or solvate isomers are a special case of ionisation isomerism in which compounds differ depending on the number of the solvent molecule directly bonded to the metal ion.