Absorbance spectroscopy relies on the fact that specific molecules can only absorb certain wavelengths. Explain how this could be used in a)microwaves and b) astronomical discoveries/interpretations. Thank you for any help with this... :)

Answer 1

a)microwave.
Veggies and meats contain fluids, mostly water. So the microwave generates a wavelength that H2O will absorb, the molecules of water vibrate and get hot, the meat/veggies are cooked. Voila!
b). If you knew the various wavelengths that can be absorbed by certain molecules, do you suppose you might be able to look at the starts and determine the gases in those starts?