the boiling point of hydrogen is 20 k. when hydrogen boils, what interactions and/or bonds are overcome?

Arock can be broken down into different kinds of substances by physical processes. no chemical reactions are needed to separate different parts of a rock into pure substances. this is because a rock is a(n)

Elements that do not have full outer electron shells will donate, share, or take electrons from other atoms. choose the items that have the correct binary ionic formula.

If you chip a tooth, most likely you will go to the dentist to have the missing material filled in. currently the material used to fill in teeth is a polymer that is flexible when put in, yet is hardened to the strength of a tooth after irradiation with blue light at a wavelength of 461 nm. what is the energy in joules for a photon of light at this wavelength?