Solid KCl, when heated with solid `K_(2)Cr_(2)O_(7)` and concentrated `H_(2)SO_(4)`, gives red vapours (a) that turn NaOH solution yellow (b). The yellow solution, when acidified with acetic acid and treated with lead acetate, gives a yellow precipitate (c). which of the following is true with respect to a, b and c?

Options

A. a nd b contain `CrO_(4)^(2-)`
B. a and c contain `CrO_(4)^(2-)`
C. a, b and c contain `CrO_(4)^(2-)`
D. a, b and c contain Cr(VI)

Answer

D