Which of the following statement is not true for the reaction given below?

${\left[\mathrm{Cu}{\left({\mathrm{H}}_2\mathrm{O}\right)}_4\right]}^{2+}+4{\mathrm{NH}}_3\rightleftharpoons {\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_4\right]}^{2+}+4{\mathrm{H}}_2\mathrm{O}$

• A

  It is a ligand substitution reaction.

• B

  ${\mathrm{NH}}_3\text{ is a relatively strong field ligand while }{\mathrm{H}}_2\mathrm{O}\text{ is a weak field ligand. }$

• C

  During the reaction, there is a change in colour from light blue to dark blue.

• D

  ${\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_4\right]}^{2+},$has a tetrahedral structure and is paramagnetic.