Acidified $KMnO_4$ is decolourised by:

Which of the following are non-metal displacement reactions?
$(A)$ $Ca_{(s)} + 2 H_2 O_{(l)} \longrightarrow Ca(OH)_{2(aq)} + H_{2(g)}$
$(B)$ $V_2 O_{5(s)} + 5 Ca_{(s)} \stackrel{\Delta}{\longrightarrow} 2 V_{(s)} + 5 CaO_{(s)}$
$(C)$ $2 Fe_{(s)} + 3 H_2 O_{(g)} \stackrel{\Delta}{\longrightarrow} Fe_2 O_{3(s)} + 3 H_{2(g)}$
$(D)$ $Cr_2 O_{3(s)} + 2 Al_{(s)} \stackrel{\Delta}{\longrightarrow} Al_2 O_{3(s)} + 2 Cr_{(s)}$

In order to oxidize a mixture of one mole of each of $FeC_2O_4$,$Fe_2(C_2O_4)_3$,$FeSO_4$ and $Fe_2(SO_4)_3$ in acidic medium,the number of moles of $KMnO_4$ required is

$SO_2$ can reduce:

Balance the following equations by the oxidation number method:
$(a) Fe^{+2} + H^{+} + Cr_2O_7^{-2} \to Cr^{+3} + Fe^{+3} + H_2O$
$(b) I_2 + NO_3^- \to NO_2 + IO_3^-$
$(c) I_2 + S_2O_3^{-2} \to I^{-} + S_4O_6^{-2}$
$(d) MnO_4^- + C_2O_4^{-2} \to Mn^{+2} + CO_2$

In which of the following reactions does $HNO_3$ $NOT$ act as an oxidizing agent?