Question

（此处省略图像相关内容，仅保留选项相关文字：选项b、c、d，以及反应进程与势能的图像相关描述，如reactants、produ、reaction progress、potential energy等）

Explanation:

To determine the correct reaction energy diagram, we analyze the potential energy of reactants and products:

Key Concept:

• Exothermic reaction: Products have lower potential energy than reactants (energy is released).
• Endothermic reaction: Products have higher potential energy than reactants (energy is absorbed).
• All reactions have an activation energy (energy barrier) that reactants must overcome to form products.

Analyzing Each Option:

• Option A: Products have higher energy than reactants (endothermic), but the activation energy path is unclear (incomplete diagram).
• Option B: Reactants and products start at the same energy, but the product energy is lower (exothermic), and there is a clear activation energy barrier (peak) — consistent with a typical exothermic reaction profile.
• Option C: No activation energy barrier (incorrect, as all reactions have an activation energy).
• Option D: Products have higher energy than reactants (endothermic), but the diagram is inconsistent (e.g., reactants’ energy is lower, and the product path is unusual).

For a valid reaction energy diagram, there must be an activation energy barrier, and the energy change (reactants → products) must be consistent. Option B shows a clear activation energy peak and products with lower energy than reactants (exothermic), which is a standard reaction profile.

Answer:

B. (The diagram labeled B, with reactants at a certain energy, a peak (activation energy), and products at lower energy than reactants)