Using the model of the periodic table, which element pictured represents an unreactive gas?

2

Explanation:

Nobel gasses are not reactive and are the far right group on the periodic table.  This is because they have a full valence electron shell which is the most stable electron configuration.  Most reactions occur in order for an atom to fill its valence shell and since they already have a full valence shell there is no reason for them to react.

altitude, density, pressure

air gets less dense the higher the altitude and also the air pressure is less as altitude rises.

i think its 5049.

i hope this !