Identify the colour of compound 'X' in the sequence of the reaction:

The purple permanganate ion $$MnO_4^-$$ is acting as an oxidising agent in the given sequence. In acidic medium it is reduced by hydrogen peroxide as follows:

$$2\,MnO_4^- + 5\,H_2O_2 + 6\,H^+ \;\longrightarrow\; 2\,Mn^{2+} + 8\,H_2O + 5\,O_2$$

The species produced after the reduction is $$Mn^{2+}$$ (compound ‘X’).

Electronic configuration of $$Mn^{2+}$$ is $$[Ar]\,3d^5$$. Although it possesses five unpaired d-electrons, d-d transitions are spin-forbidden (ΔS ≠ 0) and consequently the absorption of visible light is extremely weak; the aqueous ion appears almost colourless (very faint pink which is taken as colourless in qualitative tests).

Hence compound ‘X’ is colourless.

Option D which is: Colourless