Which of the following is the use of potassium permanganate $(KMnO_4)$?

Preparation of potassium permanganate from $MnO_2$ involves a two-step process in which the $1^{st}$ step is a reaction with $KOH$ and $KNO_3$ to produce:

$ZnO \cdot CoO$ is called

The color of acidified $K_2Cr_2O_7$ is not changed by:

$A$ purple colored compound of Manganese $(X)$ decomposes on heating to liberate oxygen and forms compounds of Manganese $(Y)$ and $(Z)$. Compound $(Z)$ reacts with $KOH$ in the presence of potassium nitrate to give compound $(Y)$. Compounds $(X)$,$(Y)$,and $(Z)$ respectively are:

Write two uses of $KMnO_4$ and $K_2Cr_2O_7$.