A. Estimate the surface gravity of a neutron star with R = 10 km and M = 2Mo. B. Determine the density of such a neutron star in g/cm³. C. How much would a teaspoon (5 cm³) of this neutron star weigh on Earth? This material is known as neutronium. Give your answer in pounds.

Which of the following statements is wrong? A. A main-sequence star is cooler and brighter than it was as a protostar.  B. Carbon fusion occurs in high-mass stars but not in low-mass stars because the cores of low-mass stars never contain significant amounts of carbon. C. when a main-sequence star exhausts its core hydrogen fuel supply, the core shrinks while the rest of the star expands. D. After a supernova explosion, the remains of the stellar core will be either a neutron star or a black hole.

In 1999, scientists discovered a new class of black holes with masses 100 to 10,000 times the mass of our sun that occupy less space than our moon. Suppose that one of these black holes has a mass of 1x10^3 suns and a radius equal to one-half the radius of our moon. What is the density of the black hole in g/cm^3? The radius of our sun is 7.0x10^5 km, and it has an average density of 1.4x10^3 kg/m^3. The diameter of the moon is 2.16x10^3 miles.

Which of the following statements about various stages of core nuclear burning (hydrogen, helium, carbon, etc.) in a high- mass star is not true? A. As each stage ends, the core shrinks and heats further. B. Each successive stage creates an element with a higher atomic number and atomic mass number. C. As each stage ends, the reactions that occurred in previous stages continue in shells around the core. D.Each successive stage lasts for approximately the same amount of time.