Hydrogen atoms are fused into deuterium, then helium-3, then helium-4, each step giving off large amounts of energy.
Explanation:
<em>Nuclear fusion</em> refers to the process in which <u>two lighter nuclei combine together to form one heavier nucleus</u>. In the Sun, hydrogen atoms combine and form helium. This process releases large amounts of energy because the helium atom has less energy than the hydrogen atoms.
