In the preparation of alkanes from hydrogenation ofalkenes and alkynes. Finely divided catalysts are used which of the following statement(s) is/are correct regarding these catalysts
(i) Platinum and palladium catalyse the reaction at room temperature.
(ii) Nickel catalyse the reaction at relatively higher temperature and pressure.
(iii) Platinum and palladium catalyse the reaction at higher temperature.

Options

A. I and iii
B. I and ii
C. ii and iii
D. I only

Answer

B

Explanation

Dihydrogen gas adds to alkenes and alkynes in the presence of finely divided catalysts like platinum, palladium or nickel to form alkanes. These metals adsorb dihydrogen gas on their surfaces and activate the hydrogen-hydrogen bond. Platinum and palladium catalyse the reaction at room temperature but relatively higher temperature and pressure are required with nickel catalyst.