Assign $A, B, C, D$ from the given type of reaction:
$2KMnO_4 \xrightarrow{\Delta} K_2MnO_4 + MnO_2 + O_2 \uparrow $

Balance the following equations in basic medium by ion-electron method and oxidation number methods and identify the oxidising agent and the reducing agent.
$(a)$ $P_{4(s)} + OH_{(aq)}^{-} \to PH_{3(g)} + HPO_{2(aq)}^{-}$
$(b)$ $N_{2}H_{4(l)} + ClO_{3(aq)}^{-} \to NO_{(g)} + Cl_{(g)}^{-}$
$(c)$ $Cl_{2}O_{7(g)} + H_{2}O_{2(aq)} \to ClO_{2(aq)}^{-} + O_{2(g)} + H^{+}$

In the reaction $Zn + 2H^{+} + 2Cl^{-} \to Zn^{2+} + 2Cl^{-} + H_2$,the spectator ion is

$Na_2S_2O_3$ reacts with moist $Cl_2$ to form $Na_2SO_4$, $HCl$, and $X$. Which one of the following is $X$?

When $SO_{2}$ is passed through acidified $K_{2}Cr_{2}O_{7}$,the process that takes place is

The value of $x$ in the partial redox equation $MnO_4^- + 8H^{+} + xe^- \rightleftharpoons Mn^{2+} + 4H_2O$ is