Atomic nuclei are made up of: a) protons and neutrons. b) protons and electrons. c) positrons and electrons. d) positrons and neutrals. e) ponytrons and nuggets. 79. Nuclei with the same number of protons, but different number of neutrons are of each other. a) isochrones b) isobars c) isotopes d) isodopes e) Isoldes 80. Thermonuclear reactions happen only in a star's core (which for the Sun is the region within about 0.25 solar radii of the Sun's center) because only there is it enough. a) cold and dilute b) hot and dense c) hot and dilute d) bland and fragile e) dirty and smudgy 81. The interior structure of a star is determined by observation, physics theory, and: a) back-of-the-envelope calculations. b) exact analytic math. c) guesswork. d) computer modeling. e) horseplay. 82. Red dwarf stars are convective: a) in no region. b) only above the photopshere. c) from center to photosphere. d) only in the nuclear burning core. e) occasionally. 83. The radius of the event horizon of a Schwarschild black hole is the radius. a) Kerr-Schwarzschild b) ergoregion c) singularity d) Schwarzschild e) right 84. A black hole that has NO angular momentum is a black hole and one does have angular momentum is a black hole. a) Kerr; Schwarzschild b) Schwarzschild; Kerr c) Einstein; Wheeler d) Wheeler; Einstein e) Tegmark; Wheeler 85. Compact, short-wavelength X-ray sources in binary systems where the source seems to have LESS than 2.2 M but more than 1.4 M are: a) probably neutron stars. b)