JEE Main · 2021 · 16 Mar 2021 · Shift 1 · Hydrocarbons

Lindlar's catalyst is finely divided palladium held on a solid carrier and partly poisoned with lead acetate or quinoline. The poison blunts the most active sites of the metal, so hydrogen adds once across the triple bond and the alkene that forms desorbs before it can be reduced further; both hydrogen atoms arrive on the same face, which makes the product the cis-alkene.
Cold dilute permanganate hydroxylates an alkene, zinc chloride with hydrochloric acid is the Lucas reagent for alcohols, and sodium in liquid ammonia reduces an alkyne to the trans-alkene by single electron transfer, so none of these is a hydrogenation catalyst.
Lindlar's catalyst is the partially deactivated palladised charcoal.