Hydrogenation of alkenes takes place in the presence of _.

Explanation

OPTION A: Hydrogenation of alkenes does not occur in the presence of simple nickel because it does not have the necessary activity and selectivity for hydrogenation reactions.OPTION B: Hydrogenation of alkenes does not take place in the presence of gold because gold is a noble metal and does not participate in chemical reactions.OPTION C: Palladium does not catalyze the addition of hydrogen to unsaturated bonds. Palladium is commonly used as a catalyst in other reactions such as the hydrogenation of nitroarenes and carbonyl compounds, but it cannot reduce alkenes to alkanes. OPTION D: The nickel is a catalyst. The hydrogen interacts with the nickel in a way that weakens the H-H bond, and thus lowers the activation energy for the hydrogenation reaction. The overall energy requirement is the same but instead of doing it in one king-hit, the catalyst permits the activation energy to be achieved in two steps, and the adsorption on the nickel holds the first step in place until the reactant arrives. Hydrogenation of alkenes and alkynes takes place in the presence of certain catalysts. In Sabatier Sendererns's reaction, the addition of hydrogen takes place in the presence of a Raney nickel catalyst.