In the following reaction mixtures,
$I$. $Cu / CuSO_4 + Ag / Ag_2SO_4$
$II$. $Zn / ZnSO_4 + Cu / CuSO_4$
copper respectively undergoes

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$N_2 + O_2 \xrightarrow{\text{High temp.}} 2NO - \text{Heat}$

If salt $Q$ undergoes a redox reaction with $H_2S$ in an acidic medium,then which of the following species cannot be a possible product?

How do you account for the following observations?
$(a)$ Though alkaline potassium permanganate and acidic potassium permanganate both are used as oxidants,yet in the manufacture of benzoic acid from toluene,we use alcoholic potassium permanganate as an oxidant. Why? Write a balanced redox equation for the reaction.
$(b)$ When concentrated sulphuric acid is added to an inorganic mixture containing chloride,we get a colourless pungent-smelling gas $HCl$,but if the mixture contains bromide,then we get red vapour of bromine. Why?

In the following reactions $(i)$ $MnO_2 + 4 HCl \rightarrow$ and $(ii)$ $2 KMnO_4 + 16 HCl \rightarrow$,the number of moles of chlorine gas released respectively are

Assign $A, B, C, D$ from the given type of reaction:
$2AgNO_3 + 2NaOH \longrightarrow Ag_2O \downarrow + 2NaNO_3 + H_2O$