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Exam1 - Grading Exam 1 Multiple Choice and Essays 1 2...

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Grading Exam 1: Multiple Choice and Essays 1 & 2 Multiple Choice: 1. B 2. A 3. B 4. D 5. C Essay 1: First 9 items=1.6 points each _ Hydrogen formed in the first few minutes after the Big Bang _ H got to Earth in the icy mantles of dust particles _ Oxygen and Iron formed in stars during fusion _ Supernovae released O & Fe to be used later _ O got to Earth in the icy mantles of dust particles _ Fe got to Earth as dust particles _ Earth formed in the collisions of dust particles/planetesimals _ Earth was radioactively heated, causing differentiation where Fe sank to the core _ Water got to the surface by being outgassed via volcanoes or acquired from comets Other items=no more than 5 points total (for inclusion of any of these) _ the atom formed much later than the nucleus _ steps of the fusion processes that lead to O/Fe _ Fe is last element formed before star explodes as supernova Essay 2: 10 pts – pick a value of R * and describe that R * is the number of stars in the galaxy divided by the age of the galaxy 3 pts – for including all intermediate numbers; listing any numbers = 2 pts
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