Answer:
I fill a room but take no space. What am I?
I may seem real but it always turns out I was never there in the first place... you only see me during a certain resting stage.
Part carbon, part water, I am poison to the fishes. Many falsely claim my name, I am the pause that refreshes. What am I?
I am rarely touched but often held and if you are smart you'll use me well.
Without me everyone would lose their head.
I am your mother's brother's only brother in law. Who am I?