Good Riddles

Question: I'm the eyelid to your life and hide you when you're inside.
You can draw me and you can pull me, but you must leave to see my good side.

What am I?

Question: If a farmer has 5 chickens, two horses, and a wife.

How many feet are on his farm?

Question: What is the coolest letter in the alphabet?

Question: I'm in everybody but everybody still wants me.
I won't feed you but I'll feed the tree.

What am I?

Question: You have found a mutant algae that doubles in size every hour. It takes 18 hours for one algae plant to take up half of a certain lake.

How long would it take for two of these plants to take up half of the same lake?