Figure 1 represents the potential energy diagram of a reaction. Pick the true statement regarding this reaction.
|A|| The reaction requires no activation energy, since it is spontaneous|
|B|| There is a net absorption of energy by the reaction|
|C|| Reactants have lower energy than that of the products|
|D|| None of the above|
Ans. D This is the potential energy diagram of a reaction. For the MCAT, you should be familiar with diagrams of this type. Since the direction of the reaction-coordinate is indicated in the diagram, we can predict the potential energy level of the reactants and the products. The bump in the graph represents the activation energy of the reaction. So Choice A doesn't make any sense. According to Choice B, there is a net absorption of energy. But in contrast to this statement, there is a net release of energy. This prediction is based on the fact that the energy level of the products is below that of the reactants. This makes Choice C wrong. That leaves us with Choice D. In fact the diagram is that of an exothermic reaction.