Using your senses like nose, mouse, hand, ears and others to gather information is called<u> observation.</u> You can get information by feeling, tasting, smelling,hearing and so on.
i think it is 8. I might be wrong.
Lead.
Lead paint was a big problem and now lead has been removed from paint because it was found to be dangerous to the health of living organisms.
Hope this helps! :)
I would agree with the second one, not the first. You can't always see the chemical reaction, and it isn't always sudden. But the second claim is true.