The reaction ${\mathrm{CH}}_3{\mathrm{COCH}}_3+4\mathrm{H}\underset{\text{ conc. }\mathrm{HCl}}{\stackrel{\mathrm{Zn}-\mathrm{Hg}}{⟶}}{\mathrm{C}}_3{\mathrm{H}}_8+{\mathrm{H}}_2\mathrm{O}$ is known as

Clemmensen reduction is used to reduce aldehydes and ketones to hydrocarbons. Zinc amalgam and concentrated hydrochloric acid are used as Clemmensen's reagent. Clemmensen reduction is a reaction which involves the reduction of a carbonyl compound to form a simple hydrocarbon. 

${\mathrm{CH}}_3{\mathrm{COCH}}_3+4\mathrm{H}\underset{\text{ conc. }\mathrm{HCl}}{\stackrel{\mathrm{Zn}-\mathrm{Hg}}{⟶}}{\mathrm{C}}_3{\mathrm{H}}_8+{\mathrm{H}}_2\mathrm{O}$