Question

Which of these is the best summary of the law of conservation of mass?

1) In a reaction, all atoms present at the beginning must be present at the end but they may be in new molecules.
2) Reactions can release energy.
3) In a reaction, substances can be destroyed.
4) Reactions create new substances.

Answer 1

The law of conservation of mass states that during a chemical reaction, mass cannot be created or destroyed, only changed in form, ensuring that the total mass of the products equals the total mass of the reactants.

Step-by-step explanation:

The best summary of the law of conservation of mass is that 'In a reaction, all atoms present at the beginning must be present at the end but they may be in new molecules.' This encapsulates the essence of the law, which states that during a chemical reaction, the total mass of the products must be equal to the total mass of the reactants. Matter, including atoms, cannot be created or destroyed in a chemical reaction; it can only change form. For example, when wood burns, the mass of the soot, ashes, and gases equals the mass of the original wood and oxygen, demonstrating that mass is conserved in the process.