Answer is: the ratio of amount NaOH reacting per unit amount FeCl₃ is 3 mol NaOH /1 mol FeCl₃.
Balanced chemical reaction:
3NaOH(aq) + FeCl₃(aq) → 3NaCl(aq) + Fe(OH)₃(s).
NaOH is sodium hydroxide.
FeCl₃ is iron(III) chloride.
Coefficient for sodium hydroxide is three and for iron(III hydroxide is one.
