Good Riddles

Question: I live with first ones ,they use me well! For the others I am hell! For the third ones I am useless,you can't touch me but you can see me! I am always there within you! Seek for me and and I'm right there! What am I?

Question: What is 5,000 years old and still turning?

Question: Name two different words using following words only... 1. Without me 60% living beinga cant survive.. 2. Without me none ( living+non-living cant survive... 3. Both have five letters each but both r anagrams of each other..

Question: A box without hinges, key or lid, yet inside, gold treasure is hid. What am I?

Question: A shield can reflect projectiles which travel at 4/5 of their original speed after being reflected. A missile is shot towards the shield at 700 km/h. At what speed did it go after its reflection?