${\mathrm{Cl}}_2$ cannot be obtained by :

The following reactions can produce chlorine gas:

A) $2{\mathrm{KMnO}}_4+16\mathrm{HCl}\stackrel{\mathrm{\Delta }}{\to }2\mathrm{KCl}+2{\mathrm{MnCl}}_2+8{\mathrm{H}}_2\mathrm{O}+5{\mathrm{Cl}}_2$

C) ${\mathrm{MnO}}_2+4\mathrm{HCl}\stackrel{\mathrm{\Delta }}{\to }{\mathrm{MnCl}}_2+2{\mathrm{H}}_2\mathrm{O}+{\mathrm{Cl}}_2$

D) $2\mathrm{KCl}+{\mathrm{F}}_2\to 2\mathrm{KF}+{\mathrm{Cl}}_2$

B) $4\mathrm{KCl}+{\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7+3{\mathrm{H}}_2{\mathrm{SO}}_4\stackrel{\mathrm{\Delta }}{\to }3{\mathrm{K}}_2{\mathrm{SO}}_4+\underset{\text{ chromylchloride }}{2{\mathrm{CrO}}_2{\mathrm{Cl}}_2\uparrow }+3{\mathrm{H}}_2\mathrm{O}$

Because of this, chlorine is not produced by the reaction in option B. The right answer is B.

Hence, heating potassium chloride with concentrated sulfuric acid does not give chlorine.