Which of the following is an example use of a noble gas? a. making steel drums c. camera batteries b. fluorescent light tubes d. xerox machines

Noble gases are very unreactive, so you're not going to see them anywhere that reactivity is important.  In fact, one of the main places they're used is in environments where reactions need to be stopped - to replace air in a reaction environment, for example.

To make steel, batteries, and Xerox machines, you wouldn't want something unreactive.  Fluorescent light bulbs ("neon bulbs"), on the other hand, fit the bill nicely.

Outermost (valence) electrons

Hairy thick gross thing? idk