An elementary classroom models a volcanic eruption by mixing vinegar and baking soda. Which of the following observations is not evidence of a chemical reaction?
Select one:

Gas bubbles formed after the vinegar and baking soda are combined.

After the substances are combined, a salt and water were formed.

The mass of the combined substances is greater then the masses of the substances separately.

The temperature of the combined vinegar and baking soda is less than the substances separately.