Answer
1 mol
Work Step by Step
Calculating how much product can be made based on the amount of each reactant, we have
$3\,mol\,Mn\times\frac{1\,mol\,Mn_{3}O_{4}}{3\,mol\,Mn}=1\,mol\,Mn_{3}O_{4}$
$3\,mol\,O_{2}\times\frac{1\,mol\,Mn_{3}O_{4}}{2\,mol\,O_{2}}=\frac{3}{2}\,mol\,Mn_{3}O_{4}$
Since $Mn$ makes the least amount of product, it is the limiting reactant.
Theoretical yield is the maximum amount of product that can be made in a reaction based on the amount of limiting reactant.
Therefore, theoretical yield= $1\,mol$.