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Chemistry Question 61 – JEE-MAIN 2026

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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.\ In the light of the above statements, choose the correct answer from the options given below :

Recall the general mechanism of heterogeneous catalysis involving transition metals, focusing on the role of their electronic configuration.

Step 1: Evaluate Statement I✦ Active

Statement I claims that first-row transition metals utilize *only* their 3d electrons for bond formation during catalysis. However, transition metals typically use both their (n−1)d and ns electrons (e.g., 3d and 4s for first-row elements) to form bonds with reactant molecules on the catalyst surface. Therefore, Statement I is incorrect.

Step 2: Evaluate Statement II○ Expand

Statement II asserts that there is an increase in reactant concentration on the catalyst surface, which is true due to adsorption. However, it also states that this process *strengthens* the bonds in reacting molecules. In reality, adsorption on the catalyst surface *weakens* the bonds within the reactant molecules, making them more susceptible to breaking and reacting. Strengthening bonds would make them less reactive. Therefore, Statement II is incorrect.

Step 3: Conclusion○ Expand

Since both Statement I and Statement II are incorrect, the correct option is the one stating that both statements are incorrect.

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