A scientist 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.

Question

A scientist 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.

anonymous · Answer

"Catching on fire" or combustion is inherently a chemical change.

anonymous · Answer

Thank you!!! Ugh I have been struggling with this question forever

anonymous · Answer

No problem! Admittedly it's a pretty strange question, since the other options are indeed things that are additional signs suggesting a potential chemical change (evolution of gas, heat, or decomposition). Burning however is most definitely always a chemical change.

anonymous · Answer

I know that's why I wasn't sure which one would be the best choice. It's a pretty crappy question.