The tail of a comet always points where?

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?

Word equation for k+ h2o yield koh + h2

What produces wave a)sound b) heats c)transfer of energy d)vibrations