Final answer:
To test the Law of Conservation of Mass while baking cookies, you can measure the mass of the ingredients before and after baking to demonstrate that the mass remains the same.
Step-by-step explanation:
The Law of Conservation of Mass states that the total mass of substances taking part in a chemical reaction is conserved during the reaction. In order to test this law while baking cookies, you can measure the mass of the ingredients used in the recipe before and after baking. For example, you can measure the mass of the flour, sugar, eggs, and butter before mixing them to make the cookie dough. Then, after baking the cookies, you can measure the mass of the baked cookies. The mass of the baked cookies should be the same as the mass of the ingredients, demonstrating that the law of conservation of mass holds true in this chemical reaction.