!!! which element has three occupied quantum shells with 4 electrons in the outermost shell

Argon. If you look at the periodic table, the noble gases (column on the furthest right of the table - labeled column 18) have fully filled electron shells. This is why noble gases (helium, neon, argon, krypton, xenon, and radon) are not very reactive with other elements - they are happy with their fully filled electron shells. So, the third element down on the noble gas column (Argon) has 3 fully filled electron shells. Periodic table courtesy of Wikipedia

(taken from Quora)

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.

the maximum mass of nh3 is nh3 in grams