A H2 molecule can be approximated by a simple harmonic oscillator having a spring constant k = 1.1 ✕ 103 N/m. (a) How many different energy transitions are possible when the H2 molecule decays from the third excited state down to the ground state?

Consider an insulating crystal, made up of layers of atoms. what form would you expect the temperature dependence of the phonon heat capacity to approach at extremely low temperatures if the interlayer coupling is i)very strong (rigid coupling), and ii) very weak. explain.