Which of the following happens during a chemical reaction?

a. atoms of reactants are destroyed.
b. new atoms are created to form the products.
c. atoms of reactants rearrange to form new substances.
d. the total mass of reactants is less than the total mass of products.

i think it's a but i'm not sure.

Option (c) is the correct answer.

Explanation:

A chemical reaction is defined as the reaction that leads to formation of new substances through exchange of electrons.

For example,

Here, aluminium on displacing copper from copper chloride leads to the formation of a new compound, that is, aluminium chloride.

Hence, it shows that atoms of reactant molecules rearrange themselves to form new substances.

Thus, we can conclude that during a chemical reaction atoms of reactants rearrange to form new substances .

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.