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 :)

i really dont know but i will try okay.

so i think u would just add all them up and get your answer..