Which of the following species is both basic and a reducing agent?

Match the following types of reactions in List-$I$ with their corresponding unbalanced equations in List-$II$.

List-$I$ (Type of reaction)	List-$II$ (Unbalanced equation)
$A$. Combination reaction	$(i)$ $AgNO_3 + CaCl_2 \longrightarrow AgCl + Ca(NO_3)_2$
$B$. Decomposition reaction	$(ii)$ $Cl_2 \longrightarrow Cl^- + ClO_3^-$
$C$. Disproportionation reaction	$(iii)$ $Mg + N_2 \longrightarrow Mg_3N_2$
$D$. Displacement reaction	$(iv)$ $KClO_3 \xrightarrow{\Delta} KCl + O_2$

Whenever a reaction between an oxidising agent and a reducing agent is carried out,a compound of lower oxidation state is formed if the reducing agent is in excess and a compound of higher oxidation state is formed if the oxidising agent is in excess. Justify this statement giving three illustrations.

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

Which of the following decolourises the colour of acidic $KMnO_4$?

By passing $H_2S$ gas in acidified $KMnO_4$ solution,we get