Answer:
I am lighter than air, but a hundred people cannot lift me. Careful, I am fragile. What am I?
I am commonly abbreviated to H
I cannot be burned in fire or drowned in water. What am I?
Brown I am and much admired. Many horses have I tried. Tire a horse and worry a man, tell me this riddle if you can. What am I?
Two in a whole and four in a pair. Six in a trio you see. Eight's a quartet but what you must get is the name that fits just one of me.
What did the piece of wood say when he saw the screwdriver and screws approaching?