Hello, Mahnoor,
2 Fe (s) + 3 S (s) --> Fe2S3 (s)
The balanced equation tells us we should expect to produce 1 mole of iron sulfide for every 2 moles of iron. This is essentialy the conversion factor we need to answer the question.
(1 mole Fe2O3)/(2 moles Fe)
Therefore,
(0.876 moles Fe)*(1 mole Fe2O3)/(2 moles Fe) = 0.438 moles Fe2O3
Bob