The Big Bang Theory allows scientists to extrapolate back in time and conclude that the universe __. Select all that apply. a) consisted of one star with eight orbiting planets b) emerged from a very tiny region and expanded c) consisted primarily of iron and nickel in the past d) was hotter and denser in the past e) consisted primarily of carbon and oxygen in the past f) was cooler and less dense in the past

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.