Question

Assertion: Concentrated ${H_2}S{O_4}$ reacts with KCl to give $C{l_2}$ gas.
Reason: HCl cannot be oxidised by concentrated ${H_2}S{O_4}$ .
(A) Both assertion and reason are CORRECT and reason is the CORRECT explanation of the assertion.
(B) Both assertion and reason are CORRECT, but reason is NOT THE CORRECT explanation of the assertion.
(C) Assertion is CORRECT, but reason is INCORRECT.
(D) Assertion is INCORRECT, but reason is CORRECT.

Answer 1

Concentrated sulphuric acid has a very powerful dehydrating property of removing water from many chemical compounds including sugar and other. Sulphuric acid is a very good oxidising agent.
Concentrated hydrochloric acid is a colourless yellowish pungent liquid. Hydrochloric acid is historically called muriatic acid. It is commonly used to make aqua regia.

Complete Step by step solution
Potassium chloride and sulphuric acid ​ reacts to give only HCl but not chlorine $C{l_2}$ gas, whereas potassium iodide and sulphuric acid reacts to liberate iodine (free halogen).
This is because bromine hydride and iodine hydride are powerful oxidising agents. Bromine hydride and iodine hydride are also thermodynamically less stable than hydrogen.
Thus, bromine hydride and iodine hydride dissociate to ${H_2}$ and ${X_2}$ ​ (X = I/Br) at higher temperatures. And conc. ${H_2}S{O_4}$ is an effective oxidising agent.
The reaction involved is as follows:
$2HX + {H_2}S{O_4} \to S{O_2} + {X_2} + {H_2}O$
for X = I/Br
HCl is only a mild reducing agent, and it is not easily oxidised to free chlorine gas by conc. ${H_2}S{O_4}$
Thus, assertion is wrong and reason is correct.
Therefore, the correct answer is option D.

Note
Some uses of sulphuric acid are as follows:
-Manufacture of fertilizers
-Production of dyes
-Manufacturing of pigments
-It is used as detergents
-It is used in petroleum refining