Calculate the wave length of an electron moving with a velocity of 2.08*10^7 ms^-1

One of the following properties was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version. which property fits this description?

In an energy pyramid, which level has the most available energy?

It is important to wear proper protective equipment in lab even when not actively performing experiments because accidents can affect any researcher, even one not working on an experiment. select the best answer from the choices provided