SPECTROSCOPY

None of these

The collimating lens

The entrance slit

The diffraction grating

at no time.

when the frequencies match exactly

at anytime.

when the amplitudes are the same.

n → σ*

n → π* and π → π*

σ → σ*

none of these

a flashlight through a prism and shake it

an Infrared spectroscopy

a large mass on a weak spring

a class of spectroscopic techniques which analyzes molecular motions

All of these

Because rotational transitions are extremely rare

Because, in liquids and solids, spectral lines corresponding to rotational transitions are broadened as the result of molecular collisions and other interactions

Because the energy required to induce a rotational transition is so small that it cannot be measured