What 2 liquids chemically react to make a solid

Why is an elements atomic mass not listed as a whole number on the periodic table

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?

Draw the lewis dot structure for each of the following polyatomic ions