In acidic medium,the moles of $KMnO_4$ required to oxidize $1.5 \, mol$ of $Cu_2S$ will be ............... $mol$.

$H_2S$ acts only as a reducing agent while $SO_2$ can act both as a reducing and oxidizing agent because

Aqueous sulphite reacts with dilute sulphuric acid to form $X_{(g)}$. The liberated $X_{(g)}$ is passed into acidified $KMnO_4$ solution. What is the oxidation state of $Mn$ in the product formed?

Which of the following reactions will lead to a redox reaction?

Balance the following equations in basic medium by the ion-electron method and identify the oxidising agent and the reducing agent.
$(a)$ $P_{4(s)} + OH^{-}_{(aq)} \rightarrow PH_{3(g)} + H_{2}P{O_{2}}^{-}_{(aq)}$
$(b)$ $N_{2}H_{4(l)} + Cl{O_{3}}^{-}_{(aq)} \rightarrow NO_{(g)} + Cl^{-}_{(g)}$
$(c)$ $Cl_{2}O_{7(g)} + H_{2}O_{2(aq)} \rightarrow Cl{O_{2}}^{-}_{(aq)} + O_{2(g)} + H^{+}_{(aq)}$

$I^{-}(aq.) + MnO_4^{-}(aq.) \xrightarrow{H^{+}} X + Mn^{2+}(aq.)$
$I^{-}(aq.) + MnO_4^{-}(aq.) \xrightarrow{\text{Neutral or weakly } OH^{-}} Y + MnO_2$
$MnO_4^{-}(aq.) + Mn^{2+}(aq.) \xrightarrow{ZnSO_4} Z + 4H^{+}$
Products $X, Y$ and $Z$ are respectively :