The reaction of P4 with X leads selectively to P4O6. The X is:
dry O2
moist O2
O2 in presence of aq. NaOH
a mixture of O2 and N2
Solution:
Phosphorus trioxide (P4O6) is prepared by heating phosphorus in the limited supply of oxygen and nitrogen. P4 + 3O2 + N2 → P4O6. N2 prevents further oxidation of P4O6 to P4O10.