Help please! What is the number that can balance the equation KClO3 → 2KCl + 3O2?

Asubstance is a good conductor of electricity which of the following best explains a probable position of the substance in a periodic table

If it is an isoelectronic series select true, if not select false. o2-, s2-, se2-, te2- na+, k+, rb+, cs+ n3-, p3-, as3-, sb3- ag, cd+, sn3+, sb4+ f-, cl-, br-, i- f-, ne, na+, mg2+ s2-, s, s6+

Why is it incorrect to balance a chemical equation by changing the subscripts? explain.