Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

The allylation of nucleophiles with allylic halides is one example of the Tsuji-Trost reactions catalyzed by this element. Eaborn discovered that it can catalyze the reaction of aryl halides with hexa-n-butyldistannane, and more broadly it underlies the reaction of vinylic and aromatic systems with organostannanes in the Kosugi-Migita-Stille coupling. Also used for the coupling of alkenes and either halides or pseudohalides in the Mizoroki-Heck reactions, this element's chloride is reduced by calcium carbonate before lead acetate is added in the creation of a catalyst which is named for Lindlar. For 10 points, name this element, the least dense of the platinum group metals.

Science