Statement I: The rate of reaction can also increase with increase in conc. of its product if one of the products acts as catalyst

Statement II: A catalyst lowers the activation energy of reactants.

Statement I and statement II are correct but statement II is not the correct explanation of statement I

Statement I: The rate of reaction can indeed increase with an increase in the concentration of its product if one of the products acts as a catalyst. Catalysts can accelerate a reaction by providing an alternative reaction pathway, reducing the activation energy, and facilitating the conversion of reactants into products.

Statement II: A catalyst does lower the activation energy of reactants. This is a fundamental characteristic of catalysts. By reducing the energy barrier for the reaction, a catalyst enables the reactants to reach the transition state more readily, leading to an increased rate of the reaction.

However, Statement II does not specifically explain or provide the reason for Statement I. The increase in the rate of reaction due to the presence of a catalyst is not solely dependent on the lowering of activation energy. Catalysts can also influence the reaction rate through other mechanisms, such as providing an alternative reaction pathway or increasing the collision frequency between reactant molecules.

Therefore, the correct answer is that both Statement I and Statement II are correct, but Statement II is not the correct explanation of Statement I.