Question

1. what is the end result of the death of an extremely high - mass star?

brown dwarf
nebula
pulsar
black hole

Explanation:

• Brown dwarfs are not formed from high - mass stars. They are objects that are not massive enough to sustain nuclear fusion like a star.
• A nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases. While stars can form from nebulae, it is not the end - result of a high - mass star's death.
• A pulsar is a highly magnetized rotating neutron star. It is formed from the collapse of a massive star, but only when the mass is not extremely high.
• When an extremely high - mass star (more than about 20 times the mass of the Sun) exhausts its nuclear fuel, it undergoes a core collapse supernova. If the remaining core is more than about 3 times the mass of the Sun, the gravitational pull is so strong that it forms a black hole.

Answer:

black hole