Answer:
NBr₃ is the excess reactant.
Explanation:
We can solve this problem by calculating how many moles of NaOH would react completely with 40 moles of NBr₃, using the stoichiometric coefficients of the reaction:
As the required number of NaOH moles is higher than the available number (60 required vs 48 available), NaOH is the limiting reactant.
As such, the excess reactant is NBr₃.