Respuesta :
Answer is: NBr₃ is the excess reactant.
Balanced chemical reaction: 2NBr₃ + 3NaOH → N₂ + 3NaBr + 3HBrO.
n(NBr₃) = 40 mol; amount of substance.
n(NaOH) = 48 mol.
From chemical reaction: n(NBr₃) : n(NaOH) = 2 : 3.
40 mol : n(NaOH) = 2 : 3.
n(NaOH) = 60 mol; for 40 moles of NBr₃, 60 moles of NaOH is needed, because there is only 48 moles, not all NBr₃ will react (onl 32 moles, 16 moles are excess).