Question

HELP ASAP!! An experiment is performed in which a crystalline substance is added to a beaker filled with room-temperature water. The following observations were made:

1. The crystals dissolve.
2. A precipitate forms.
3. The bottom of the beaker feels warm to the touch.
4. Bubbles begin to form in the water.
Which observations are evidence that a chemical reaction took place?

Answer 1

observations 2, 3, and 4 indicate that a chemical reaction has occurred.

Answer 2

observations (2), (3), and (4) provide strong evidence that a chemical reaction occurred.

Step-by-step explanation:

Observations (2), (3), and (4) are evidence of a chemical reaction because a precipitate formed, energy was released (the bottom of the beaker felt warm), and bubbles were formed in the water. Observation (1) indicates a physical change, not a chemical reaction.