HCl was passed through a solution of  ${\mathrm{CaCl}}_2 , {\mathrm{MgCl}}_2$and $\mathrm{NaCl}$. Which of the following compound(s) crystallise(s) ?

Solubility of NaCl is less than  ${\mathrm{CaCl}}_2 \mathrm{and} {\mathrm{MgCl}}_2$.On passing HCl through the saturated solution of NaCl containing ${\mathrm{CaCl}}_2$ and ${\mathrm{MgCl}}_2$ , NaCl only precipitates, because its Ionic product $\left({\mathrm{K}}_{\mathrm{IP}}\right)$ exceeds solubility product most easily.