What Am I Riddles

Question: Round like a apple, deep like a cup, but all the kings horses can't pull it up.

What is it?

Question: What has no beginning, end, or middle?

Question: I move faster in certain solids, but slower in certain gases. I am typically broken by objects with large masses. I can be used as for pleasure, practice, and even an alarm. If used excessively, I can cause harm. What am I?

Question: Give me food, and I will live. Give me water, and I will die. What am I?

Question: The more you work, the more I'll eat.You keep me full, I'll keep you neat. What am I?