In the p-p chain, shown in the above diagram, what particles must be input in order to produce one 4He nucleus?
A: 8 protons, but 2 of them are returned when the 4He is produced B: 6 protons, but 2 of them are returned when the 4He is produced C: 2 photons and 2 positrons D: 2 protons and 4 neutrons E: 4 neutrons
In what box does the galaxy in the bottom center belong in this Hubble tuning fork diagram?
A: E1 B: Irr C: Sc D: SBb E: SBc
In the figure above, how would you calculate the fraction of the mass of the gas in the universe that is in the form of Helium?
A: take 4x4 for the mass of Helium and divide by 4x4+48x1 for the total mass B: take 4x1 for the mass of Helium and divide by 48x1 for mass of Hydrogen C: take 4 for the mass of Helium an divide by 48 for the mass of Hydrogen D: take 48x1 for the mass of Hydrogen and divide by 4x4+48x1 for total mass E: take 48x4 for the mass of Hydrogen and divide by 4x1 + 48x4 for total mass