A student conducts an investigation using mall spares. In one part of the investigation, he needs to closely examine a spore sample. Whach piece of equipment does the student need to we to keep mekl spares from entering his respiratory system?

In 2002, the rare earth elements mine in mountain pass, california was closed because

What is the percentage of hydrogen in nitrogen trihydride

Select all of the statements which are true. electrons are located in shells or orbits around the atom. electrons orbit slowly around the atom. electrons travel in one flat path around the nucleus of an atom. the valence of an atom is determined by the number of electrons in the atom's outermost shell.