What Am I Riddles

Question: What is red and white at home, but can never be that when it leaves?

Question: What can you smell but not see. And can be deadly, too.

Question: I am the thing that is used to make your weight. What am i?

Question: I can hurt and make people bleed when I'm on the dark side, but used in good ways and I can also help you. What am I?

Question: Unexpected is my arrival. It is announced to all nearby. I protect you, yet you try to supress me. With my friends I embarrass you. What am I?