Good Riddles

Question: The more you add, the less it weighs.

Question: There is a chain nailed to the wall. The chain is 10 feet long and the center of the chain dips down 5 feet from where each side of the chain is nailed to the wall. How far are the 2 ends of chain from each other?

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?

Question: A natural state, I'm sought by all.
Go without me, and you shall fall.
You do me when you spend,
and use me when you eat to no end.

What am I?

Question: In the middle of winter, a woman is found dead in her bed, with multiple stab wounds in the stomach. Soaked into the sheets is a massive amount of blood, along with blood drops on the carpet. On the side table beside her bed, there is a glass full of water mixed with blood. What was the murder weapon, where is it now, and how was she killed?