In $Cr_2O_7^{2-}$,every $Cr$ is linked to

Acidified chromic acid $+ H_2O_2 \xrightarrow{\text{Org. solvent}} X + Y$ (blue colour). $X$ and $Y$ are:

On heating potassium permanganate,one of the following compounds is not obtained:

When a mixture of $NaCl$,$K_{2}Cr_{2}O_{7}$ and conc. $H_{2}SO_{4}$ is heated in a dry test tube,a red vapour $(X)$ is evolved. This vapour $(X)$ turns an aqueous solution of $NaOH$ yellow due to the formation of $Y$. $X$ and $Y$,respectively,are

Which diagram correctly represents the change in the color of an aqueous solution of chromate ions?

$A$ group of acidic oxides is