Logic Riddles

Question: Something you know nobody knows, and everyone knows something you don't. We all know something, nobody knows everything, and you know something someone doesn't know. What else could nobody know?

Question: Have a question , regardless you ask any people , that people only give you answer is " no " , what is this question ??

Question: You need a room for your group. Each person needs 5 square feet of space. You have 25 people in your group, what is the smallest room you can use?

Question: What goes up white and comes down yellow?

Question: I always wait unit you're off guard or get older so you can become easier to attack. Once your body is weak, I strike inside you and try to kill you. What am i