Why must a chemical equation be balanced before you can determine mole ratios

A chemical equation must be balanced before you can determine the mole ratio due to the law of conservation of mass... you cannot get more product than the reactant you feed into the reaction and in turn you cannot get less product than the reactant you put in. You must have the same going in as you have coming out...

With out balancing the equation this law would not be met and you would not be receiving accurate calculations.

1.from liquid state to gaseous state is evaporation 3.solid to liquid is melting 5. solid to gaseous state is sublimation 6. gas to solid state is decomposition 7. a change of state is known as the states of matters

Yes you are correct use the scientific method