Answer:
I am so delicate that even mentioning me breaks me. What am I?
Sometimes dark and sometimes bright, I make my way among twinkling lights. Seas and oceans obey my call, yet mountains I cannot move at all. What am I?
The more you work the more I'll eat.You keep me full I'll keep you neat.
I know a word of letters three. Add two and fewer there will be. What is the word?
I don't live within a house nor do I live without. Most will use me when they come in and again when they go out.
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.