Good Riddles

Question: You feel me but can't touch me, you can hear me but can't see me. I move leaves in trees, you need me to live. At my highest speeds i uproot trees and mow down houses. I cause waves over the ocean. I've been around since the beginning of life. What am I?

Question: Can you make VI out of IX?

Question: Spell "Hard Water" using only 3 letters.

Question: You have 20 sick sheep, one dies. How many are left?

Question: There are 100 coins scattered in a dark room. 90 have heads facing up and 10 are facing tails up. You cannot tell which coins are which. How do you sort the coins into two piles that contain the same number of tails up coins?