Question

how many oxygen atoms are there in 1g of O2

Answer 1

1 mole of O2 =6.022* 10^23 O2 molecules

1 O2 molecule contains 2 O atoms

Therefore,

No.of O atoms in 1 mole of O2 molecule = 2*6.022 *10^ 23 atoms

12.044*10^23 atoms 
I HOPE IT HELPS YOU :(

Answer 2

no. of moles = mass / molar mass 
                    = 1/ 32                           (molar mass of O is 16 but here 2 oxygene
                                                             so 16+16=32)
   no. of atom in 1 mole of O is Na(avogadro no.)
 so in 1/32 moles the no. of atom is = 1/32 * avogadro no.(Na)