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becx777

Answer:

2. A piece of metal is placed in water and produces sparks and gas

Explanation:

The production of gas is usually a sign of a chemical reaction.  The metal is reacting with the water to form a new substance (the gas).

Incorrect answers and why:

1.  Changing colors can be a sign of a chemical reaction, but in this case it's more likely that the colors blended together.  (If it was something like two clear liquids combining to form a yellow liquid, then it would be more clear evidence of a chemical reaction)

3.  The liquid is boiling

4.  The powder dissolved into the liquid

I hope this helps!

The answer is not B because a new substance is not created, they just produced sparks and gas. The answer is not C because the liquid is still THE liquid even if it starts to boil. The answer is not D because that is a physical change called dissolving. So the answer would have to be A; blue liquid is mixed into a yellow liquid, and the mixture turns green. The two substances are being mixed together and created a new substance. Also a sign of chemical reaction is color change.