Good Riddles

Question: What's the difference between a well-dressed man on a bicycle and a poorly-dressed man on a tricycle?

Question: Light hides me and darkness kills me.

What am I?

Question: I am a big threat to humanity,
but you wouldn't get rid of me even if you could.

What am I?

Question: You work at a factory that produces dumbbell weights for lifting. One of the 10 machines has been producing weights that are always 1 pound less than the rest of the machines. You have a large scale used to weigh the weights for quality control. How could you find the defective machine by using the scale only once? You are allowed to make as many weights with the machines as you please.

Question: You're in a room with no doors or windows. Just a mirror and a table.

How do you get out?