Nitrogen is used in the food packaging industry because it _______.

______ and ______ are the two gases, which when taken together make $99\%$ of air.

I. Nitrogen

II. carbon dioxide

III. Noble gases

IV. Oxygen

_____ can be seen moving in a beam of sunlight in a dark room. (Options: water droplets, Dust particles, Nitrogen gas, Oxygen gas)

[Note: Options are given to avoid any ambiguity]