Question

Given below are two statements for catalytic properties of transition metals.
Statement I: First row transition metals which act as catalyst utilise their 3d electrons only for formation of bonds between reactant molecules and atoms on the surface of catalyst.
Statement II: There is increase in the concentration of reactants on the surface of catalyst which strengthens the bonds in reacting molecules.

• A. Both Statement I and Statement II are correct
• B. Both Statement I and Statement II are incorrect
• C. Statement I is correct but Statement II is incorrect
• D. Statement I is incorrect but Statement II is correct

Answer 1

The Correct Option is B

Step 1: Analyze Statement I.
First row transition metals act as catalysts by interacting with reactant molecules through the electrons present in their 3d, 4s, and 4p orbitals. The assumption that only the 3d electrons are involved in the formation of bonds with reactants is incorrect. While 3d electrons play a crucial role in bonding and electron transfer, they are not the sole contributors. The 4s and 4p orbitals are also involved in bonding, especially during the adsorption of reactants on the catalyst surface. The catalytic process is a complex interaction involving all these electron orbitals, which helps lower the activation energy of the reaction. Therefore, Statement I, which claims that only 3d electrons are involved, is incorrect.

Step 2: Analyze Statement II.
The statement that there is an increase in the concentration of reactants on the catalyst surface is generally true because a catalyst provides a surface for the reactants to adsorb and undergo the reaction. However, the claim that this increase in concentration strengthens the bonds in reacting molecules is misleading. In reality, catalysts function by weakening certain bonds in the reactant molecules, making it easier for the reaction to proceed. The interaction with the catalyst surface often leads to the weakening of the bonds between atoms in the reactants, facilitating the breaking of bonds and the formation of new ones. The catalyst does not strengthen bonds in the reactants, but rather lowers the activation energy of the reaction, making it easier for the reaction to occur. Therefore, Statement II is also incorrect.

Step 3: Conclusion.
Since both Statement I and Statement II contain misconceptions about the role of transition metals in catalysis, both are incorrect. The catalytic process involves the interaction of multiple electron orbitals, and catalysts work by weakening bonds in reactants, not strengthening them. Hence, both statements fail to accurately describe the catalytic properties of transition metals.