6. Which statement is true about all metals? A) They are attracted to a magnet.
B) They are weak and brittle.
C) They may be used to form alloys.
D) They react with water.

This is the process of diffusion and is exhibited by gases. The compounds responsible for the smell of onions are released into the air and diffuse through out the house due to random molecular movement. This allows you to smell them at the entrance of your house.