PLEASE HELP PLS What is the alkaline earth metal with valence electrons in the 3rd energy level?
А: Magnesium
B: Calcium
C: Sodium
D: Aluminum

Ibeg i need 20. a reaction produces 4.93 l of oxygen, but was supposed to produce 1 mol of oxygen. what is the percent yield?

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

Silver tarnishes as silver metal reacts with hydrogen sulfide, h2s, in the air. in this reaction, dark silver sulfide, au2s, covers the surface of silver. when silver is polished, this coating of silver sulfide can be removed from the surface. this makes the silver shiny again. enter the coefficients that balance the tarnishing reaction equation. (type 1 for no coefficient.)