When balancing a chemical equation, what may be changed so that the atoms match on both sides?

1. Balancing an equation makes the atom count match, because atoms are conserved. 2. Coefficients can be placed in front of the reactants and products until the counts agree. 3. A coefficient says how many units of that substance take part. 4. Subscripts inside a formula may never be touched, because changing them changes the substance itself. 5. Changing a subscript would turn water into hydrogen peroxide, which is a different compound. 6. The element symbols and the arrow are fixed by the reaction being described. 7. After balancing, always recount the atoms of each element on both sides as a check. _Source: Siyavula Physical Sciences Grade 10 (Everything Science, CC BY 4.0), Chapter 14: Representing chemical change_