Please I really need help with this

Asingle atom of an element has 21 neutrons, 20 electrons, and 20 protons. which element is it? ok o z

You have 125g of a certain seasoning and are told that it contains 76.0 g of salt what is the percentage of salt by mass in this seasoning

An alkaline battery produces electrical energy according to the following equation. zn(s) + 2 mno2(s) + h2o(l) zn(oh)2(s) + mn2o3(s) (a) determine the limiting reactant if 17.5 g zn and 31.0 g mno2 are used. (type your answer using the format ch4 for ch4.) (b) determine the mass of zn(oh)2 produced. _ g