Potassium dichromate when heated with concentrated sulphuric acid and a soluble chloride,gives brown-red vapours of:

Which one of the following sulphides is yellow?

Which of the following statements is not correct?

The orange colour of $K_2Cr_2O_7$ and purple colour of $KMnO_4$ is due to

Which of the following ions is green in colour?

$Cr_2O_7^{2-} / H^{\oplus}$ $\xrightarrow[200^{\circ}C]{H_2O_2} 'X'$ $\xrightarrow{\text{On Standing}} 'Y'_{(aq. sol)}$
Select the correct option for $'X'$ and $'Y'$