Aliquid that occupies a volume 4.7 has a mass of 5.1kg .what is the density of the liquid in kg/l?

What elements have 2 electrons inthe 4s sublevel

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?

How might this scientific phenomena be explained? a paper clip floats on water.