Chromatographic technique/s based on the principle of differential adsorption is / are

A. Column chromatography

B. Thin layer chromatography

C. Paper chromatography

Choose the most appropriate answer from the options given below:

In chromyl chloride test for confirmation of $$\mathrm{Cl}^{-}$$ ion, a yellow solution is obtained. Acidification of the solution and addition of amyl alcohol and $$10 \% \mathrm{~H}_2 \mathrm{O}_2$$ turns organic layer blue indicating formation of chromium pentoxide. The oxidation state of chromium in that is

Appearance of blood red colour, on treatment of the sodium fusion extract of an organic compound with $$\mathrm{FeSO}_4$$ in presence of concentrated $$\mathrm{H}_2 \mathrm{SO}_4$$ indicates the presence of element/s

The technique used for purification of steam volatile water immiscible substances is :