Which of the following best describes the reaction that occurs when hydrogen-iodide is cooled? A It is a physical reaction because the number of atoms are the same. It is a physical reaction because the number of atoms are the same.

B It is a physical reaction because the number of molecules is the same. It is a physical reaction because the number of molecules is the same.

C It is a chemical reaction because the atoms are arranged in the same way. It is a chemical reaction because the atoms are arranged in the same way.

D It is a chemical reaction because the atoms are rearranged into new molecules.