20 points! asp! your answer must be explained! how is a pure substance different from a mixture? a. mixtures cannot be separated by physical means b. mixtures are made up of more than one component c. a pure substance is heterogeneous d. pure substances are separated by physical means

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?