1. which of the following is true regarding the law of conservation of mass? a it dictates that the number of molecules on each side of a chemical equation must be the same. b it does not apply to chemical reactions. c it dictates that the number of atoms of each element must be the same on both sides of a chemical equation. d it states that the mass of the reactants must remain constant in order for a chemical reaction to proceed.

C It dictates that the number of atoms of each element must be the same on both sides of a chemical equation.  

Step-by-step explanation:

Atoms have mass, so they can neither be destroyed nor created.

Thus, the number of atoms of each element must be the same on both sides of a balanced chemical equation.  

A is wrong. Molecules consist of different numbers of atoms, and it is atoms that must be conserved.

B is wrong. the Law of conservation of Mass applies to all chemical reactions.

D is wrong. If the reaction proceeds, the mass of reactants must decrease as they are converted to products.

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !