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

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

In Carius tube, an organic compound '$$\mathrm{X}$$' is treated with sodium peroxide to form a mineral acid 'Y'.

The solution of $$\mathrm{BaCl}_{2}$$ is added to '$$\mathrm{Y}$$' to form a precipitate 'Z'. 'Z' is used for the quantitative estimation of an extra element. '$$\mathrm{X}$$' could be