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?

(N/A) Toluene is a non-polar organic compound,while $KMnO_4$ is an ionic,polar inorganic compound. They are immiscible in water. Alcohol acts as a mutual solvent for both,facilitating the reaction.
The balanced redox equation for the oxidation of toluene to benzoate in an alkaline medium is:
$C_6H_5CH_3 + 2MnO_4^- + OH^- \rightarrow C_6H_5COO^- + 2MnO_2 + 2H_2O$
$(b)$ Concentrated $H_2SO_4$ acts as both an acid and an oxidising agent. With chloride salts,it produces $HCl$ gas,which is not further oxidised by $H_2SO_4$. However,with bromide salts,the $HBr$ produced is a stronger reducing agent and is further oxidised by concentrated $H_2SO_4$ to $Br_2$ (red vapours):
$2HBr + H_2SO_4 \rightarrow Br_2 + SO_2 + 2H_2O$