Answer:An endothermic reaction
Explanation: In an endothermic reaction, it takes more energy to break the bonds of the reactants than is released when the bonds in the products are formed. In an endothermic reaction, the temperature goes down.
I believe that the correct answer would be energy since you need energy for any kind of chemical change to occur. I hope this helped you with your question! If you have any questions please let me know and I might be able to further assist you.
Answer:
Iodine has more electron levels (rings) than fluorine.
Explanation:
On the periodic table, fluorine is on period 2 so it has 2 outer rings, iodine is on period 5 so it has 5 outer rings. The more rings the higher radius.