Why is mars visible from earth in the night sky

The difference between the atomic number of an element and the element’s atomic mass is the number of ions.

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 do you determine the percent yield of a chemical reaction