What Am I Riddles

Question: I fasten to walk,
and unfasten to stop.

What am I?

Question: What can you put in your mouth, but not swallow?

Question: you have two liquid substances in a sealed jar one yellow one white, they stay separate even when shaken. When poured out the white substance turns clear what am i?

Question: Decapitate me and all becomes equal. Then truncate me and I become second. Cut me front and back and I become two less than I started. What am I?

Question: Black within and red without with four corners roundabout.