Final answer:
When a massive star exhausts its supply of hydrogen fuel, it becomes a supernova. This is because the star's iron core collapses, forming a neutron star and leading to a type II supernova explosion.
Step-by-step explanation:
When a massive star exhausts its supply of hydrogen fuel, it becomes a supernova. This statement is true. In a massive star, hydrogen fusion in the core is followed by several other fusion reactions involving heavier elements. Just before it exhausts all sources of energy, a massive star has an iron core surrounded by shells of silicon, sulfur, oxygen, neon, carbon, helium, and hydrogen.
The fusion of iron requires energy (rather than releasing it). If the mass of a star's iron core exceeds the Chandrasekhar limit (but is less than 3 Msun), the core collapses until its density exceeds that of an atomic nucleus, forming a neutron star with a typical diameter of 20 kilometers. The core rebounds and transfers energy outward, blowing off the outer layers of the star in a type II supernova explosion. So, when a massive star runs out of hydrogen fuel, it undergoes a supernova explosion.