What is not represented by a balanced chemical equation?

1) The same number of atoms is on each side of the equation.

2) The formulas for all substances are correct.

3) The same mass is represented on each side of the equation.

4) The same subscripts are on each side of the equation.

Answer is: 4) The same subscripts are on each side of the equation.

For example, balanced chemical reaction:

2Mg + O₂ → 2MgO.

1) The same number of atoms is on each side of the equation: two magnesium atoms and two oxgen atoms.

2) The formulas for all substances are correct: in magnesium oxide (MgO), magnesium has oxidation number + 2 and oxygen - 2, so formula is good, because compound must be neutral.

3) The same mass is represented on each side of the equation: because there is same number of atoms, the mass is the same.

4) The same subscripts are on each side of the equation: oxygen does not have same subscripts.