Ascientist is performing an experiment on a powder. which of the following is a sign that a chemical change has definitely occurred during his experiment?
the powder catches on fire.
the powder releases bubbles.
the powder heats up.
the powder breaks apart into smaller particles.

The best and most correct answer among the choices provided by the question is the first choice "the powder catches fire"

Chemical change is any change that results in the formation of new chemical substances. At the molecular level, chemical change involves making or breaking of bonds between atoms. These changes are chemical: iron rusting (iron oxide forms) gasoline burning (water vapor and carbon dioxide form)


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Answer/// he concludes that the atom particles can be broken due to the paddle wheel being moved by particles coming out of the metal;