Reaction by which Benzaldehyde cannot be prepared:

$\displaystyle +\mathrm{CrO}_2 \mathrm{Cl}_2$ in $\displaystyle \mathrm{CS}_2$ followed by $\displaystyle \mathrm{H}_3 \mathrm{O}^{+}$

$\displaystyle +\mathrm{H}_2$ in presence of $\displaystyle \mathrm{Pd}-\mathrm{BaSO}_4$

$\displaystyle +\mathrm{CO}+\mathrm{HCl}$ in presence of anhydrous $\displaystyle \mathrm{AlCl}_3$

$\displaystyle +\mathrm{Zn} / \mathrm{Hg}$ and conc. HCl