$\mathrm{R}-\mathrm{X}\left(\mathrm{X}=\mathrm{Cl},\text{ Br, I}\right)+{\mathrm{H}}_2\stackrel{\mathrm{Zn}/{\mathrm{H}}^{+}}{\to }\mathrm{RH}+\mathrm{HX}$

This reaction is called 

When alkyl halides are reduced by zinc and dil. Hcl in to alkanes .This reaction is known as reduction reaction.