Question

Catalytic activity of transition metals depend on
A) Their ability to exist in different oxidation states
B) The size of the metal atom
C) The number of empty atomic orbital available
D) All of the above

Answer 1

Hint: Transition metals and their compounds are known for their homogeneous and heterogeneous catalytic activity. Catalytic activity of substances is its ability to increase the rate of a reaction by lowering the activation energy of the reaction.

Complete answer:
The catalytic activity of transition metal depends on –
First of all we need to understand about the transition metals.
Transition metals are metallic elements such as chromium, iron and nickel with electronic configuration $\left( {n - 1} \right){d^{1 - 9}}n{s^{1 - 2}}$.
They have valence electrons in two shells instead of only one. Before talking about the catalytic activity of transition metals, we need to understand about the work of a catalyst.
Catalysts work by catalytic pathways. They increase the rate of a reaction without affecting the thermodynamics. They provide an alternative lower energy pathway for the reaction to take place.
The most important reason that transition metals are good catalysts is because they can easily lend or with raw electrons from the reagents, that is, they have the ability to exist in a variety of oxidation states. This is due to the low energy gap between possible oxidation states.

Thus, option (A) is the correct option.

Note: Students might get confused on Transition metals with ‘d - block’ metals in the periodic table. Although transition metal belongs to the d-block of the periodic table, not all d - block elements are transition metals. Only those d - block metals which have incompletely filled d - orbital are transition metals. Zinc $\left( {3{d^{10}}4{s^2}} \right)$ is thus d-block metal but not transition metal.