In basic solution above ` pH 6, CrO_(3) ` forms the tetrahedral yellow chromate ion, `CrO_(4)^(2-)`. Between pH 2 and 6, `HCrO_(4)^(-)` and the orange

In basic solution above ` pH 6, CrO_(3) ` forms the tetrahedral yellow chromate ion, `CrO_(4)^(2-)`. Between pH 2 and 6, `HCrO_(4)^(-)` and the orange red dichromate dichromate ion, `Cr_(2)O_(7)^(2-)`, are in equilibrium. At pH values below 1, the main species is `H_(2)PCrO_(4)`. The equilibria are
`HCrO_(4)^(-) hArr CrO_(4)^(2-) + H^(+), K = 10^(-5.9)`
`H_(2) CrO_(4) hArr HCrO_(4)^(-) + H^(+), K = 4.1`
`Cr_(2)O_(7)^(2-)+H_(2)O iff 2HCrO_(4)^(-),K=10^(-2.2)`
In addition, these are base- hydrolysis equilibria
`Cr_(2)O_(7)^(2-)+OH^(+) iff HCrO_(4)^(-)+CrO_(4)^(2-)`
`HCrO_(4)^(-)+OH^(-) iff CrO_(4)^(2-) iff CrO_(4)^(2-) +H_(2)O`
The pH dependent equilibria are quite labile and on addition of cations that form insoluble chromates (e.g., `Ba^(2+),Pb^(2+) " and " Ag^(+)`), the chromates and not the dichromates are precipitated.
The equilibria,
(a) ` Cr_(2)O_(7)^(2-) iff 2CrO_(4)^(2-)` is shifted to right in
A. An acidic medium
B. A basic medium
C. A neutral medium
D. It does not exist.