the mass of chemical a is 2 g, and the mass of chemical b is 5 g. if the two chemicals are mixed and a
chemical reaction takes place, what is the mass of the end products?

2 g of A react with 5 g of B. After the chemical reaction takes place, the mass of the end products is 7 g.

Let's consider the following generic reaction.

A + B ⇒ Products

According to Lavoisier's law of conservation of mass, matter is not created nor destroyed over the course of a chemical reaction.

Thus, the mass of the reactants before the reaction must be equal to the mass of the products after the reaction.

2 g of A react with 5 g of B. After the chemical reaction takes place, the mass of the end products is 7 g.

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Explanation:

The Law of Conservation of Mass states that matter cannot be destroyed or created.

That is, the total mass before and after the reaction stays the same.

                  A + B ⟶ C

mass/g:      2    7        x

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.