See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Concept: In a potential energy diagram (also called a reaction energy profile), different points on the curve correspond to different chemical species or states along the reaction coordinate. Reasoning: 1. Point W is at a local minimum on the left side of the diagram — this represents the reactant(s), the starting material with relatively low potential energy. 2. Point X is at the maximum (peak) of the energy curve — this is the highest-energy point along the reaction pathway. 3. Point Y is at a local minimum on the right side — this represents the product(s), which are at lower energy than X but lower than W, indicating an exothermic reaction. Key principle: A maximum on a potential energy diagram corresponds to a transition state (also called an activated complex). The transition state is an unstable, high-energy species that cannot be isolated; it exists at the top of the energy barrier separating reactants from products. Why other options fail: - (b) A reaction intermediate appears as a local minimum between two maxima on the diagram (i.e., a valley between two peaks). Point X is a maximum, not a minimum, so it cannot be an intermediate. - (c) A resonance hybrid is a stable weighted average of resonance structures of a molecule; it is not a point on an energy diagram. - (d) A reactant corresponds to the starting point W (the local minimum on the left), not X. Therefore, the correct answer is A.