$(NH_4)_2Cr_2O_7$ (Ammonium dichromate) is used in fireworks. The green coloured powder blown in air is

$KMnO_4$ reacts with ferrous ammonium sulphate according to the equation
$MnO_4^- + 5Fe^{2+} + 8H^+ \to Mn^{2+} + 5Fe^{3+} + 4H_2O$
Here $10 \ mL$ of $0.1 \ M$ $KMnO_4$ is equivalent to:

Consider the following reaction:
$MnO_2 + KOH + O_2 \rightarrow A + H_2O$
Product '$A$' in neutral or acidic medium disproportionates to give products '$B$' and '$C$' along with water. The sum of spin-only magnetic moment values of '$B$' and '$C$' is . . . . . $BM$. (nearest integer)
(Given atomic number of $Mn$ is $25$)

In which of the following reactions does $HNO_3$ $NOT$ act as an oxidizing agent?

Suggest a scheme of classification of the following redox reactions:
$(a) N_{2(g)} + O_{2(g)} \rightarrow 2NO_{(g)}$
$(b) 2Pb(NO_3)_{2(s)} \rightarrow 2PbO_{(s)} + 4NO_{2(g)} + O_{2(g)}$
$(c) NaH_{(s)} + H_2O_{(l)} \rightarrow NaOH_{(aq)} + H_{2(g)}$
$(d) 2NO_{2(g)} + 2OH^{-}_{(aq)} \rightarrow NO_2^-(aq) + NO_3^-(aq) + H_2O_{(l)}$

Acidified potassium permanganate solution is decolourised by