Which of the following is a sign a chemical reaction has occurred?
A blue liquid is mixed into a yellow liquid, and the mixture turns green.
A piece of metal is placed in water and produces sparks and gas.
Aliquid is heated on a hotplate, and bubbles form.
A solid powder is mixed into a liquid and disappears.

A liquid is heated on a hot plate, and bubbles form

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.

you did not give any options thus this is the best answer i can give to you with this little information you have given

> they are both natural and not man made

> they can be tracked and predicted by the right tools

-love shrooms