(a) Mass of one atom of oxygen

1 mole of oxygen atom = 16 gm = 6.022 x 10²³ atoms

∴ Mass of one atom of oxygen = \(\frac{16}{6.022 \times 10^{23}}\) = 2.65 x 10²³

(b) Mass of one molecule of oxygen

1 molecule of oxygen = O₂

= 2 x 16

= 32 u

(c) Mass of one mole of oxygen gas

1 mole of oxygen gas is O₂ = 32 u

(d) Mass of one ion of oxygen

1 mole of oxygen = 6.022 x 10²³ atoms = 16 g

Mass of one ion of oxygen = \(\frac{16}{6.022 \times 10^{23}}\)

= 2.65 x 10^-23

(e) Number of atoms in one mole of oxygen molecule

1 mole of oxygen molecule i.e.,

O₂ = 6.022 x 10²³ molecules.

1 molecule of O₂ = 2 atoms.

∴ Number of atoms in 1 mole of oxygen molecule = 6.022 x 10²³ x 2 atoms

= 1.2044 x 10²⁴