They are called "black holes".
The most massive stars become black holes.
Yes. They get sucked into black holes all the time!
False. Only the most massive stars will become black holes.
No. They do not have enough mass to become black holes. Depending on the mass they will either become white dwarfs or neutron stars.
Most stars end up as white dwarfs. A few become neutron stars. Even fewer become black holes.
False. Medium-sized stars become white dwarfs. Only the most massive stars form black holes.
Black holes
Only stars that are much more massive than our sun can become a black hole. When the star dies, it explodes (called a supernova) and then gravitational collapse helps it to form a black hole.
The difference is in mass. Low to medium mass stars (up to about 8-10 solar masses) become white dwarfs. Massive stars (10 to 25 solar masses) become neutron stars. Stars above 25 solar masses tend to become black holes.
The most massive stars will die as black holes.
High-mass stars might become black holes, if the remaining matter (after the supernova explosion) is sufficiently large.
Not really "a" black hole - many black holes. It is currently believed that all, or most, galaxies have a huge black hole at its center. Any galaxy should also have lots of smaller black holes - so-called "stellar" black holes, because they have approximately the mass of a star (larger stars can become black holes).