A study of the Earth by The National Aeronautics and Space Administration (NASA) determined there were 7.80×1011 tons of carbon stored in living plants on the Earth's surface, at the time of the study. Calculate the mass of carbon stored in these plants in grams. (1 ton equals 907.19 kg)

The nuclear potential that binds protons and neutrons in the nucleus of an atom is often approximated by a square well. imagine a proton conned in an innite square well of length 105 nm, a typical nuclear diameter. calculate the wavelength and energy associated with the photon that is emitted when the proton undergoes a transition from the rst excited state (n 2) to the ground state (n 1). in what region of the electromagnetic spectrum does this wavelength belong?