The weight of silver (atomic weight=108) displaced by a quantity of electricity which displaces 5600 ml of O2 at STP will be:

At STP, 1 mole of oxygen occupies 22400 mL.
Hence, the number of moles of oxygen corresponding to 5600 ml is
NO2 = 5600/22400 = 1/4 = WO2/MO2.
1 mole of oxygen produces 4 moles of electrons and 1 mole of silver requires 1 mole of electrons.
WAg/MAg × 1 = WO2/MO2 × 4
WAg/108 = (1/4) × 4
WAg = 108g
Thus, the weight of silver displaced by a quantity of electricity which displaces 5600 ml of O2 at STP will be 108.0 g.