Addition takes place according to Markownikoff’s rule in which $C{l^ + }$ goes to that carbon atom which is more hydrogenated.
$(1)$ $CH_3 - C \equiv C - CH_3$ $(2)$ $CH_3CH_2CH_2CH_3$
$(3)$ $CH_3CH_2C \equiv CH$ $(4)$ $CH_3CH = CH_2$

${C_2}{H_2}\xrightarrow{{{O_3}}}X\xrightarrow{{Zn/C{H_3}COOH}}Y$