In the reaction,$2KMnO_4 + 16HCl \rightarrow 5Cl_2 + 2MnCl_2 + 2KCl + 8H_2O$,the reduction product is

What is the four-electron reduced form of $O_2$?

$Zn^{2+}_{(aq)} + 2e^- \to Zn_{(s)}$. This is

$A$ sulphur molecule is converted into a sulphide ion when it:

If an atom undergoes reduction,its oxidation number......

When an acidified solution of ferrous ammonium sulphate is treated with potassium permanganate solution,the ion which is oxidised is