$A$ compound of mercury used in cosmetics,in Ayurvedic and Yunani medicines and known as vermilion is

The starting material for the manufacture of $KMnO_4$ is

Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with $(i)$ iron $(II)$ ions,$(ii)$ $SO_2$,and $(iii)$ oxalic acid? Write the ionic equations for the reactions.

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

$Fe(OH)_2$ is precipitated from $Fe(II)$ solutions as a white solid but turns dark green and then brown due to the formation of:

Which of the following is incorrect about $K_{2}Cr_{2}O_{7}$?