Assign reasons for the following:
Transition metals and their many compounds act as good catalyst.

Transition metals acts as catalyst due to the following reasons:
(i) Their partially empty d-orbitals provide surface area for reactant molecules.
(ii) They combine with reactant molecules to form transition states and lowers their activation energy.
(iii) They show multiple oxidation states and by giving electrons to reactants they form complexes and lower their energies.0

V₂O₅ (in contact process for manufacture of H₂SO₄), finely divided iron (in Haeber’s process for NH₃ manufacture) and Ni (in catalytic hydrogenation) are examples of their good catalytic activities.