Question

Oxidation of which of the following reagent with manganese dioxide $\left( {Mn{O_2}} \right)$ gives chlorine $?$
(A) Conc. $HCl$
(B) Dil. $HCl$
(C) ${H_2}S{O_4}$
(D) $HN{O_3}$

Answer 1

Hint : Oxidation occurs when an atom, molecule, or ion loses one or more electrons in a chemical reaction. When oxidation occurs, the oxidation state of the chemical species increases. The term oxidation was originally used to describe reactions in which an element combines with oxygen. Example: The reaction between magnesium metal and oxygen to form magnesium oxide involves the oxidation of magnesium.

Complete Step By Step Answer:
$Mn{O_2}$ is a mild oxidizing agent that selectively oxidizes primary or secondary allylic and benzylic alcohols.
Oxidation of $HCl$ (conc.) with manganese dioxide (MnO2​) gives chlorine.
The reaction involved can be written as:
$Mn{O_2} + 4HCl \to MnC{l_2} + 2{H_2}O + C{l_2}$
Hence the correct Option is A. Conc. $HCl$

Additional Information:
The term oxidation was first used to describe reactions in which metals react with oxygen in air to produce metal oxides. For example, when iron is exposed to air in the presence of water, the iron turns to rust and gives an iron oxide.

Note :
Oxidation occurs when a reactant loses electrons during the reaction. Reduction occurs when a reactant gains electrons during the reaction. This often occurs when metals are reacted with acid. An oxidation-reduction (redox) reaction is a chemical reaction that involves a transfer of electrons between two species. This reaction the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.