Fe and Cr both are getting oxidised.
Fe oxidation state is changing from +2 (in FeCr2O4 ) to +3 (in Fe2O3) and
Cr from +3 (in FeCr2O4 ) to +6 (in K2CrO4)
Fe2+→Fe3++e−
Cr6+2→2Cr3++6e−
----------------------------------------------------
FeCr2O4→Fe2O3+K2CrO4+7e−
So 7 moles of electrons are produced per mole of FeCr2O4