Molecular mass or molecular weight means to the mass of a molecule .it is calculated as the sum of mass of each constituent atom multiplied  by the number of atoms of that element in the molecular formula. the average mass of a molecule of a substance in atomic mass unit is called its molecular mass 
The Brainliest Answer!
Molecular mass of sub. =  mass of 1 mole of its molecules.
so here, mass of 1 molecule is  5.32 *10∧-23
and so, mass of 1 mole of molecule is  6.022* 10∧23 (Avogadro constant)

∴ moleculer mass of sub is equal to the mass of it 6.022* 10∧23 molecules 

 so,mass of 1 molecules of subtance                     = 5.32* 10∧-23
      mass for 6.022 *10∧23 molecules of subtance = ?
                                                                          =5.32* 10∧-23 ×6.022* 10∧23 
                                                                          = 32 g
and the 32g moleculer mass is for O2
so, the sub is O2
2 4 2