How can ionic compounds dissolve in water?

In this chemical reaction, 325 grams of barium (ba) react completely. how many moles of lithium (li) are produced?

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?

Stage in which a star’s outer layers have started to cool and grow outward?