What is the oxidation number for each atom in nh4ci?

The mass has escaped into a gas which you can not see so the law stays true.

The total number of nucleons

So the main goal for the elements is stability which is a complete/full valence shell and typically the magic number for a stable element is 8 valence electron but not always. so elements to the left of the periodic table tend to be way less stable then those on the right, so the elements on the left are much more reactive.

Beaker test tube ..i think