Statement I: ${\mathrm{Ni}}^{2+}$ with DMG shows red colouration.

Statement II : Both ${\mathrm{Fe}}^{2+} \text{and} {\mathrm{Fe}}^{3+}$ are blue coloured.

An ammoniacal metal salt solution gives a brilliant red precipitate on addition of dimethylglyoxime. The metal ion is :

Why is ammonium chloride added to the solution during the precipitation of Nickel $\left(\mathrm{II}\right)$ ion with hydrogen sulphide?

Why ${\mathrm{H}}_2\mathrm{S}$ is passed after addition ${\mathrm{NH}}_4\mathrm{Cl}$ and ${\mathrm{NH}}_4\mathrm{OH}$?

Which of the following complexes is formed during the cyanide test for nickel(II) ions?

In the cyanide test for nickel, what is the colour of the precipitate formed?

What type of reaction occurs between nickel ions and bromine water during the test?

Which colour precipitate is observed when bromine water and excess of $\mathrm{NaOH}$reacts with a solution containing nickel ions?

Given below are two statements :
Statement (I) : Dimethyl glyoxime forms a six membered covalent chelate when treated with ${\mathrm{NiCl}}_2$ solution in presence of ${\mathrm{NH}}_4\mathrm{OH}.$
Statement (II) : Prussian blue precipitate contains iron both in $\left(+2\right)$ and $\left(+3\right)$ oxidation states.

In the light of the above statements, choose the most appropriate answer from the options given below: