Question

match the statements with graph a or b. has an activation energy. has a +δh. has a -δh. exothermic. endothermic.

Explanation:

Step1: Analyze activation energy concept

All chemical reactions have an activation - energy barrier, so both graphs A and B have an activation energy.

Step2: Analyze $\Delta H$ sign

In an endothermic reaction, the products have higher energy than the reactants, so $\Delta H>0$. In graph B, the products have higher energy than the reactants, so it has a $+\Delta H$. In an exothermic reaction, the products have lower energy than the reactants, so $\Delta H < 0$. In graph A, the products have lower energy than the reactants, so it has a $-\Delta H$.

Step3: Determine exothermic and endothermic

Exothermic reactions release heat and have products with lower energy (graph A). Endothermic reactions absorb heat and have products with higher energy (graph B).

Answer:

Has an activation energy: A, B
Has a $+\Delta H$: B
Has a $-\Delta H$: A
Exothermic: A
Endothermic: B