Which of the following is a sign a chemical reaction has occurred? a liquid changes to a solid when cooled. a liquid forms bubbles when heated. two clear liquids combine and mix together. two clear liquids combine and turn cloudy.

The best answer is, “Two clear liquids combine and turn cloudy.”

When water freezes form a liquid to a solid. That’s a physical change.

When water boils, it forms bubbles. That’s a physical change.

When you mix ethanol and water, they form a clear solution. That’s a physical change.

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.

the food using pesticides in the future will harm you by giving you diseases like cancer or something since they have things that we should not eat in it like chemicals or pesticides. that is why organic food is more expensive because they take the time to make it right and healthy for you to eat.

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