Lower ionization energy means that it is easier or harder to remove an electron

1st step : find the number of moles for the known substance

number of moles =mass/ relative molecular mass

n=23/Li2O2

n=23/(14+32)

n =23/46

n= 0,5moles

2nd step : balance the equation

2Li202 +2H20> 4LiOH +O2

3rd step : find the mole ratio of the known or stated using the balanced equation

Li2O2 : O2

2 : 1

4th step :find the number of moles for the asked using the mole ratio using simple proportion

Li2O2 :O2

2 :1

0,5 :???

0,5/2 ×1

= 0,25moles for (O2)

5th step : find the asked either mass , volume , concentration

number of moles = volume/molar gas volume

volume = number of moles × molar gas volume

v = 0,25moles × 28dm^3

v= 7 dm^3 of (O2)