Which of these events indicate that a chemical reaction might have occurred?

A: Silver jewelry becomes dark because of tarnish

D: A solid appears when two water-based solutions are together

When silver tarnishes, the color change shows that a new substance is produced. Likewise, the precipitate forming from two water-based solutions shows that a new substance is produced. So, these two events are chemical reactions.

I hope this helps :)

the arctic is a region of the planet, north of the arctic circle, and includes the arctic ocean, greenland, baffin island, other smaller northern islands, and the far northern parts of europe, russia (siberia), alaska and canada.

i dont know but

explanation:

whoever your teacher is, deserves a raise for using pokemon as an example