Give the main product of the following reactions:
$(i)$ $1, 2-$dibromopropane + alcoholic $KOH$
$(ii)$ $1, 1, 2, 2-$tetrabromoethane + zinc powder in methanol

(N/A) $(i)$ The reaction of $1, 2-$dibromopropane with alcoholic $KOH$ undergoes dehydrohalogenation to form propene:
$CH_3CHBrCH_2Br + 2KOH \xrightarrow{\text{alcoholic}} CH_3CH=CH_2 + 2KBr + 2H_2O$
$(ii)$ The reaction of $1, 1, 2, 2-$tetrabromoethane with zinc powder in methanol undergoes debromination to form ethyne:
$CHBr_2-CHBr_2 + 2Zn \xrightarrow{CH_3OH, \Delta} CH \equiv CH + 2ZnBr_2$