Ontario Grade 9 Science Class Practice Exam 2026 - Free Grade 9 Science Practice Questions and Study Guide

Nuclear fusion is the process in which two or more atomic nuclei combine to form a heavier nucleus, releasing large amounts of energy in the process. This process is the opposite of nuclear fission, which is the splitting of a heavy nucleus into two lighter nuclei. Option C is incorrect because it describes sublimation, not nuclear fusion. Option D is incorrect because nuclear fusion involves the changing of the nucleus of an atom.