`K_2Cr_2O_7` acts as a good oxidizing agent in acidic medium `underset("Orange")(Cr_(2)O_(7)^(2-)) + 14H^(+) + 6e^(-) rarr underset("Green")(2Cr^(3+)) + 7H_2O`
In alkaline solution, orange colour of `Cr_(2)O_(7)^(2-)` chages to yellow colour due to formation of `Cr_2O_(4)^(2-)` and again yellow colour changes to orange colour on changing the solution to acidic medium
`underset("Orange")(Cr_2O_7^(2-))+2OH^(_) rarrunderset("Yellow")(Cr_2O_7^(2-))+H_2O`
`underset("Yellow")(2CrO_(4)^(2_-)) + 2H^(+) rarr underset("Orange")(Cr_(2)O_(7)^(2-) + H_(2)O)`
`Cr_(4)^(2-) and Cr_(2)O_(7)^(2-)` exist in equilibrium at pH =4 and are interconvertible by altering the pH of the solution. When heated with `H_2SO_4` and metal chloride `K_2Cr_2O_7` gives vapour of chromyl chloride `(CrO_2Cl_2)` . Chromyl chloride `(CrO_2Cl_2)` when passed into aqueous NaOH solution, yellow colour solution of `CrO_(4)^(2-)` is obtained. This on reaction with lead acetate gives yellow ppt. `PbCrO_4` . When `H_2O_2` is added to an acidified solution of dichromate ion, a complicated reaction occurs. The products obtained depend on the pH and concentration of dichromate.
`Cr_2O_7^(2-)+2H^(+) + 4H_(2)O_(2) rarr 2Cr(O_2)+5H_2O`
A deep blue-violet coloured peroxo compound, `CrO(O_2)_2,`' called chromic peroxide is formed. This decomposes rapidly in aqueous solution into `Cr^(3+)` and xygen.
`CrO_3` on reaction with HCl and the product on reaction with NaOH(aq) give respectively

Options

A. `CrO_(2)Cl,CrO_(4)^(2-)`
B. `Cr(OH)_2,CrO_(4)^(2-)`
C. `Cl_(2),Cr_(2)O_(7)^(2-)`
D. `Cl_(2).Cr(OH)_3`

Answer

A

Explanation

`Cl^(+) + CrO_3 rarr CrO_2Cl_2`