When copper is added to concentrated $H_2SO_4$,$CuSO_4$ is produced along with another sulphur-containing compound $X$. The compound $X$ is

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

List-$I$ $(\text{Redox Reaction})$	List-$II$ $(\text{Type of Redox Reaction})$
$A$. $CH_{4(g)} + 2O_{2(g)} \xrightarrow{\Delta} CO_{2(g)} + 2H_2O_{(l)}$	$I$. Disproportionation reaction
$B$. $2NaH_{(s)} \xrightarrow{\Delta} 2Na_{(s)} + H_{2(g)}$	$II$. Combination reaction
$C$. $V_2O_{5(s)} + 5Ca_{(s)} \xrightarrow{\Delta} 2V_{(s)} + 5CaO_{(s)}$	$III$. Decomposition reaction
$D$. $2H_2O_{2(aq)} \xrightarrow{\Delta} 2H_2O_{(l)} + O_{2(g)}$	$IV$. Displacement reaction

Choose the correct answer from the options given below:

Match the reactions in Column $I$ with the nature of the reactions/type of the products in Column $II$.

Column $I$	Column $II$
$A$. $O_2^{-} \rightarrow O_2 + O_2^{2-}$	$p$. redox reaction
$B$. $CrO_4^{2-} + H^{+} \rightarrow$	$q$. one of the products has trigonal planar structure
$C$. $MnO_4^{-} + NO_2^{-} + H^{+} \rightarrow$	$r$. dimeric bridged tetrahedral metal ion
$D$. $NO_3^{-} + H_2SO_4 + Fe^{2+} \rightarrow$	$s$. disproportionation

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

Light green crystals of ferrous sulphate lose water molecules and turn brown on exposure to air. This is due to its oxidation to:

$KMnO_4$ (acidified) $+ HCl \rightarrow H_2O + X_{(g)},$ $X$ is a