Question

The mass in a chemical reaction remains constant. Why?​

Answer 1

Answer:

According to the law of conservation of mass, matter can neither be created nor destroyed, so the total quantity of matter, i.e., the total mass, before and after a change, remains the same. So, the mass of the substances, taken together, before and after a chemical change, will also remain same. From this, it can be concluded that any new substance formed during a chemical change is due to the rearrangement of the atoms of the original substance. The number of atoms of each kind remains the same, before and after the chemical change.

Answer 2

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$\dashrightarrow$Atoms are not created or destroyed in a chemical reaction, they are just rearranged from the reactants to form the products. ... If a chemical reaction is completed in a closed system (when nothing extra can get in and nothing can escape), then the mass will remain constant