How many oxygen atoms are required during complete oxidation of 1 molecule of PGAL in aerobic respiration?

For the complete oxidation of one molecule of glucose, 6 molecules of oxygen is required or 12 atoms of oxygen is required. 1 glucose molecule undergoes glycolysis to produce 1 molecule of PGAL and 1 molecule of DHAP. As we have only 1 molecule of PGAL as substrate. Therefore, the oxygen requirement will be half. Therefore, for oxidation of 1 molecule of PGAL there is requirement of 3 molecules or 6 atoms of oxygen.