Assign $A, B, C, D$ from the given type of reaction.
$3PbS + 8HNO_3 \text{ (dil.)} \longrightarrow 3Pb(NO_3)_2 + 3S \downarrow + 2NO + 4H_2O$

In the reaction between hydrogen sulphide and acidified permanganate solution,which of the following occurs?

In the thermal decomposition of a metal carbonate,the oxidation state of the metal changes if the metal is

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

The number of electrons involved in the reduction of permanganate to manganese dioxide in acidic medium is $.......$.

In the balanced chemical reaction
$IO_3^- + aI^- + bH^+ \to cH_2O + dI_2$
$a, b, c, d$ respectively correspond to