What maximum fraction of the air in the room could be displaced by the gaseous nitrogen?

The atmosphere is made up of different gases. The air in any room can be likened to the air outside and so the same proportions of gases would apply. The air surrounding the earth is composed of 78% nitrogen, 21% oxygen, 1% argon and trace amounts of other gases including carbon dioxide. These values indicate therefore that the maximum fraction to be displaced is 78%. 

Ions gain or lose electrons