Question

reactants vs. products quick check
according to the law of conservation of mass, which statement about chemical reactions is always true? (1 point)
the number of molecules in the reactants is the same as the number of molecules in the products.
the number of atoms of each element in the reactants is the same as the number of atoms of each element in the products.
the states of the substances in the reactants is the same as the states of the substances in the products.
the number of substances in the reactants is the same as the number substances in the products.

Explanation:

The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. This means that the atoms of each element in the reactants are just rearranged to form products. The number of atoms of each element must remain the same before (reactants) and after (products) the reaction. The number of molecules can change (e.g., in \(2H_2 + O_2
ightarrow 2H_2O\), there are 3 molecules of reactants and 2 molecules of products). The states of substances (e.g., gas, liquid, solid) can change (e.g., in \(H_2O(l)
ightarrow H_2O(g)\)). The number of substances can change (e.g., decomposition reactions like \(2H_2O
ightarrow 2H_2 + O_2\) where 1 substance decomposes into 2 substances).

Answer:

The number of atoms of each element in the reactants is the same as the number of atoms of each element in the products.