Answer:
I hope what I put is correct. If it isn't, I'm sorry.
Step-by-step explanation:
Correct: 1,5,7
Not too sure: 3(I think it's incorrect)
Incorrect: 2(it also has a grammar error?),4, 6, 8
Dashes are used in the beginning and end of a series. These would otherwise cause confusion. For example, "The three elements - earth, water, and fire - worked together."
To test if a dash makes sense, pause wherever there is a dash while reading the sentence out loud. Does it make sense to pause there? If yes, then usually the dash is correct. If no, the dash is not correct.