Which of these is true about pure substances?

a. they can only contain one type of atom
b. they can only contain one type of molecule
c. they may contain one type of atom or one type of molecule
d. they can contain different types of atoms and molecules

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?