Hello Dear,

Molecular weight of oxygen is 32.Thus the number of moles present in 16 g of O2 will be 0.5 Number of molecules present will be 0.5NA Number of gram atoms will be 0.5×2NA=NA( Since one molecule of oxygen contains 2 atoms of oxygen)1 mol of a gas occupies 22.4l at STP, thus given sample will occupy 11.2l at STP.No. of protons=No.of gram atoms×8=8NA(Since one oxygen atom contains 8 protons)

Good Luck