5 grams will be left. After the first 1000 years, there will be half of 20 left, or 10. After 2000 years, half of 10 will remain, which is 5.
Answer:
Neutron stars are one of the possible ends for a star. They result from massive stars which have mass greater than 4 to 8 times that of our Sun. After these stars have finished burning their nuclear fuel, they undergo a supernova explosion. ... It collapses so much that protons and electrons combine to form neutrons.
