Give the hydrogenation and halogenation reactions of alkynes.

(N/A) Hydrogenation of alkyne: Alkynes react with dihydrogen in the presence of catalysts like $Pt$,$Pd$,or $Ni$ to form alkanes.
$CH_3-C \equiv CH + H_2$ $\xrightarrow{Pt/Pd/Ni/\Delta} [CH_3CH=CH_2]$ $\xrightarrow{H_2} CH_3-CH_2-CH_3$ (Propane)
$(b)$ Halogenation of alkyne: Alkynes react with halogens (like $Br_2$ in $CCl_4$) to form tetrahaloalkanes. The discharge of the reddish-orange color of bromine solution serves as a test for unsaturation.
$CH_3-C \equiv CH + Br_2$ $\xrightarrow{CCl_4} [CH_3CBr=CHBr]$ $\xrightarrow{Br_2} CH_3CBr_2-CHBr_2$ ($1$,$1$,$2$,$2$-Tetrabromopropane)
Rate of reaction: $Cl_2 > Br_2 > I_2$