Acidic ferric chloride solution on treatment with excess of potassium ferrocyanide gives a Prussian blue coloured colloidal species. It is:
\( \mathrm{KFe[Fe(CN)_6]} \)
\( \mathrm{K_5Fe[Fe(CN)_6]_2} \)
\( \mathrm{Fe_4[Fe(CN)_6]_3} \)
\( \mathrm{HFe[Fe(CN)_6]} \)