Answer : When addition of [tex]H_2[/tex] to 2-pentyne in the presence of the Lindlar's catalyst will produce cis-2-pentene.
Explanation :
Role of Lindlar's catalyst :
It is a deactivated catalyst having [tex]Pd/CaCO_3[/tex] in lead acetate poisoned with small amount of quinoline and is used for the reduction of alkynes to cis-alkenes.
When addition of [tex]H_2[/tex] to 2-pentyne in the presence of the Lindlar's catalyst will produce cis-2-pentene.
The chemical reaction is shown below.