3) the atomic number of magnesium is 12. this means that its nucleus must contain a) 6 protons and 6 neutrons. b) 6 neutrons and 6 electrons. \c) 12 neutrons and no protons. d) 12 protons and no electrons.

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Atypical jetliner lands at a speed of 146 mi/h and decelerates at the rate of (10.4 mi/h)/s. if the jetliner travels at a constant speed of 146 mi/h for 1.5 s after landing before applying the brakes, what is the total displacement of the jetliner between touchdown on the runway and coming to rest?

What practical value did astronomy offer to ancient civilizations?