When a mixture of solid $\mathrm{NaCl}$ and solid  ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ is heated with concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$, deep red vapours are obtained. This is due to the formation of:

Due to the formation of chromyl chloride mixture of solid  $\mathrm{NaCl}$ and ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ is heated with  concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ deep red vapours are obtained

In the reaction,

$4\mathrm{NaCl}+{\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7+3{\mathrm{H}}_2{\mathrm{SO}}_4\to \underset{ }{2{\mathrm{CrO}}_2{\mathrm{Cl}}_2}+2{\mathrm{Na}}_2{\mathrm{SO}}_4+{\mathrm{K}}_2{\mathrm{SO}}_4+3{\mathrm{H}}_2\mathrm{O}$Here, the correct option is chromyl chloride.