If a white dwarf's mass exceeds the Chandrasekhar limit, what happens?

• A. It remains a white dwarf
• B. It collapses into a neutron star or black hole
• C. It expands indefinitely
• D. It turns into a red giant

Answer: (B)

When a white dwarf’s mass goes beyond the Chandrasekhar limit, gravity overcomes the electron degeneracy pressure that currently supports the star. The white dwarf can’t stay in stable equilibrium any longer, so it collapses. As it collapses, it becomes an extremely dense object: a neutron star if the mass is within a certain range, or, for even larger masses, it can continue collapsing into a black hole. This is why the best answer is that it collapses into a neutron star or black hole. The other options don’t fit because a mass above the limit cannot remain a white dwarf, cannot expand indefinitely, and wouldn’t simply turn into a red giant in this context.