Which of the following statements is incorrect for $KMnO_4$?

Amphoteric oxide$(s)$ of $Mn$ is/are:

Which of the following is most basic in nature?

Which of the following compositions is found in dental amalgam alloys?

Consider the following reactions:
$NaCl + K_{2}Cr_{2}O_{7} + H_{2}SO_{4}$ (conc.) $\rightarrow (A) +$ side products
$(A) + NaOH \rightarrow (B) +$ side product
$(B) + H_{2}SO_{4}$ (dilute) $+ H_{2}O_{2} \rightarrow (C) +$ side product
The sum of the total number of atoms in one molecule each of $(A)$,$(B)$,and $(C)$ is:

What are the oxidation states of iron in the minerals hematite and magnetite?