Answer:
A compound has atoms of different elements chemically joined together They can't be separated without a chemical reaction.
Pure substance element I think
Answer:19. He says that he’s been really tired since several weeks ago. 20. A friend of us is going to pick us up at the airport. 21. I’ve worked like a waiter in the past, but I wouldn’t want to do it again. 22
Explanation:
Because matter cannot be created or destroyed
