Fun Riddles

Question: I am taken from a mine, and shut up in a wooden case, from which I am never released, and yet I am used by almost everybody.

What am I?

Question: Why did the chicken cross the road?

Question: What is the best way to keep your hat from falling off your head?

Question: Something different to show every week, but I'm still the same place.
If you're eating it's probably butter that you taste.

What am I?

Question: A very famous chemist was found murdered in his kitchen today. The police have narrowed it down to six suspects. They know it was a two man job. Their names: Felice, Maxwell, Archibald, Nicolas, Jordan, and Xavier.

A note was also found with the body: '26-3-58/28-27-57-16'.

Who are the killers?