What is always true according to the Law of Conservation of Matter?

Question

1. Atoms can be rearranged during a chemical reaction but cannot be added or taken away.
2. Atoms created during a chemical reaction must have the same mass as the atoms in the reactants.
3. New molecules cannot be formed from the reactants during a chemical reaction.
4. The total number of molecules before and after a chemical reaction stays the same.

Answer 1

According to the Law of Conservation of Matter, the statement that is always true is:

1. Atoms can be rearranged during a chemical reaction but cannot be added or taken away.

This law states that matter cannot be created or destroyed in a chemical reaction, meaning the total number of atoms remains the same before and after the reaction; they are simply rearranged to form new substances.

The other options have inaccuracies: 2. Atoms created during a chemical reaction must have the same mass as the atoms in the reactants — while the total mass remains constant, the statement implies creation, which contradicts the law. 3. New molecules can indeed be formed from the reactants during a chemical reaction; this is a core aspect of chemical reactions. 4. The total number of molecules before and after a chemical reaction does not necessarily stay the same; it is the number of atoms that must remain constant, while the number of molecules can change as they are rearranged into different forms.

So, option 1 is the correct answer.