A test tube becomes cool to the touch.
Explanation:
The signs for an endothermic reaction would most likely be that a test tube becomes cool to touch. An endothermic reaction is a reaction in which heat is absorbed from the environment.
- At the end of this heat change, the surrounding becomes colder.
- Most endothermic reactions are always shown by the test tube becoming colder.
- For exothermic reaction in which heat is given off to the surroundings, the tube should be hotter.
Learn more:
Exothermic reactions brainly.com/question/10567109
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