How many moles of water are produced if 5.43 mol PbO2 are consumed?

Each mole of PbO2 contains 2 moles of oxygen (O). Thus there would be 5.43x2 = 10.86 moles O.
Each mole of water (H2O) contains 1 mole of O, so from 10.86 moles of O you could get 10.86 moles of H2O.