Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$FeSO_4 + Na_2S \longrightarrow FeS \downarrow$

Which of the following will not change the orange colour of $K_2Cr_2O_7$ into green colour in an acidic medium?

When $SO_2$ is bubbled into an acidic $KMnO_4$ solution,decolorization of the purple solution takes place along with the formation of a manganese compound $X$. Under neutral conditions,compound $X$ reacts with $KMnO_4$ in the presence of zinc oxide to give another manganese compound $Y$. The oxidation states of manganese in compounds $X$ and $Y$,respectively,are

Match List-$I$ with the List-$II$.

List-$I$ (Reaction)	List-$II$ (Type of redox reaction)
$A$. $N_{2(g)} + O_{2(g)} \rightarrow 2 NO_{(g)}$	$I$. Decomposition
$B$. $2 Pb(NO_3)_{2(s)} \rightarrow 2 PbO_{(s)} + 4 NO_{2(g)} + O_{2(g)}$	$II$. Displacement
$C$. $2 Na_{(s)} + 2 H_2 O_{(l)} \rightarrow 2 NaOH_{(aq)} + H_{2(g)}$	$III$. Disproportionation
$D$. $2 NO_{2(g)} + 2 OH^-_{(aq)} \rightarrow NO^-_{2(aq)} + NO^-_{3(aq)} + H_2 O_{(l)}$	$IV$. Combination

Choose the correct answer from the options given below:

Ferrous sulphate on strong heating gives:

$KMnO_4$ reacts with oxalic acid according to the equation:
$2MnO_4^- + 5C_2O_4^{2-} + 16H^+ \to 2Mn^{2+} + 10CO_2 + 8H_2O$
Here $20 \ mL$ of $0.1 \ M \ KMnO_4$ is equivalent to: