Assign $A, B, C, D$ from the given type of reaction.
$ZnSO_4 \, (aq) + MgCl_2 \, (aq) \longrightarrow$ No reaction

One litre of $0.15 \ M \ Na_2SO_3$ aqueous solution is mixed with $500 \ mL$ of $0.2 \ M \ K_2Cr_2O_7$ aqueous solution in acid medium. What is the concentration (in $mol \ L^{-1}$) of unreacted $K_2Cr_2O_7$ in the resultant solution?

The oxidation state of copper changes when aqueous copper $(II)$ ions react with
$(I)$ $NaOH_{(aq)}$
$(II)$ $Fe_{(s)}$
$(III)$ $KI_{(aq)}$

$KMnO_4$ oxidises $S_2O_3^{2-}$ to $SO_4^{2-}$ in medium $x$ and $NO_2^-$ to $NO_3^-$ in medium $y$. $x$ and $y$ are respectively:

In the reaction $I_2 + 2S_2O_3^{2-} \to 2I^{-} + S_4O_6^{2-}$,the equivalent weight of iodine will be equal to

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