A coloured compound (A) reacts with dilute `H_(2)SO_(4)` to produce a colourless gas (B) and colourless solution (C). The reaction between (B) and the acidified `K_(2)Cr_(2)O_(7)` solution produces a green solution and a slightly yellowise precipitate (D). the substance (D) burns in air to produce a gas (E) which also can change the colour of `K_(2)Cr_(2)O_(7)` solution.
Q. When colourless solution (C) reacts with `Pb_(3)O_(4)//H^(+)`, it acquires a violet red colour due to formation of
A. `MnO_(4)^(-)`
B. `PbO_(2)`
C. `I_(3)^(2-)`
D. `[Ni(en)_(3)]S_(2)O_(3)`
