What Am I Riddles

Question: I'm in everybody but everybody still wants me.
I won't feed you but I'll feed the tree.

What am I?

Question: I stand in one place yet I fill a whole room.
I can be filled with molten rock and come in every hue.

What am I?

Question: I am an instrument that you can hear, but you can not touch or see me.

What am I?

Question: You wear me every day but you never put me on.
I will change colors if you leave me out too long.

What am I?

Question: What gets longer when pulled,fits between breasts, slides neatly into a hole,has choked people when used improperly,and works best when jerked?