Good Riddles

Question: Mr. Niceguy donated one million dollars to help feed starving people. After he donated the money he was a millionaire.

How did he become a millionaire?

Question: What is bright and sunny?

Question: I can pogo on the moon, but not Mars. I can pogo on this table, but not on a stick. What can assure us to be able to pogo on objects at all times?

Question: What is green and has wheels?

Question: What temperature is twice as hot as 0 degrees Celsius?