True or false? Please explain especially if the statement is false.

(a) To be IR active, a polyatomic molecule must possess a permanent dipole moment. (b) The fluorescence spectrum of a molecule occurs at a shorter wavelength than the absorption spectrum of the molecule.

(c) A 600-MHz NMR spectrometer is more sensitive than a 400-MHz spectrometer.

(d) Whenever a molecule goes from one energy level to another, it must emit or absorb a photon whose energy is equal to the energy difference between the two levels.