Water boiling is an example of a physical change. The rest are chemical changes.
Hope that helps!!
I think the correct answer would be that the temperature of the clouds that made the very first stars where thought to be higher since the clouds are made up of hydrogen and helium. Hope this answers the question. Have a nice day.
Answer: Fusion
Explanation:
Combustion is a chemical reaction in which hydrocarbons are burnt in the presence of oxygen to give carbon dioxide and water.
Nuclear fusion is a process which involves the conversion of two small nuclei to form a heavy nuclei along with release of energy.

Nuclear fission is a process which involves the conversion of a heavier nuclei into two or more small and stable nuclei along with the release of energy.
