Question

Which of the following MUST be the same before and after a chemical reaction?
1. The total mass of the reactants and total mass of the products.
2. The number of molecules of each substance involved in the chemical reaction.
3. The number of atoms of each element involved in the chemical reaction.

Answer 1

Answer:

For any chemical reaction , the mass of the reactants before the reaction should be equal to the mass of products formed after the reaction .

So , your answer will be option A

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Answer 2

Answer:

1. The total mass of the reactants and total mass of the products.

3. The number of atoms of each element involved in the chemical reaction.

Explanation:

concept - acc. to law of conservation of law The total mass of the reactants and total mass of the products. or mass can neither be created nor it can be destroyed.

And also The number of atoms of each element involved in the chemical reaction.

so 1 statement The total mass of the reactants and total mass of the products.

and 3 statement The number of atoms of each element involved in the chemical reaction

both are correct

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