Question

if a reaction is reversibel what are the relative amounts of reactants

Answer 1

That's not an easy question to answer. It depends on a lot of things. It will vary depending on the specific chemical system being considered. Things like the temperature of the pressure could cause changes. In a closed system, reactant and product concentrations will eventually reach a stable equilibrium condition. The relative amounts of reactants and products at equilibrium is determined by an equilibrium constant, found by applying the mass action law. In other words, it's complicated and you will likely study it in more advanced chemistry courses.