according to the balanced reaction equation:
2KClO3→ 2KCl + 3O2
from this equation, we can see that the molar ratio between KCl & O2 is 2 : 3
so, 2 moles of KCl will need 3 moles of O2
∴ 7.16 moles of KCl will need X moles of O2
∴number of moles of O produced = 7.16 * 3 / 2
= 10.74 moles