Logic Riddles

Question: A man wanted to enter and exclusive club, but did not know the password to get in. He waited by the door and listened. The doorman said "Twelve" and the other man said "Six" and was let in. A second member came up and the doorman said "Six" to which the member replied "Three" and was let in. The man went up and the doorman said to him "Ten" the doorman said "Five" but was not let in. Why?

Question: What number when divided in half becomes zero?

Question: How much does it worth to shoot a free throw in a game of basketball?

Question: A chicken gives meat and egg while cow gives us milk. Find another who gives us all these?

Question: If there's a pound of lead and feather, which is heavier?