Which best describes what is occurring in the reaction? When vinegar and baking soda react, the mixture becomes cold to the touch and a gas and a new liquid substance are formed.

The formation of a gas and a new liquid substance shows that a chemical reaction is occurring. Because the mixture becomes cold, it takes in heat from its surroundings, so the reaction is endothermic. Therefore, the best choice is “The reaction is chemical and endothermic.”

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