One mole of a substance is the mass of a substance which contains exactly 6.023 x 10²³ molecules or atoms of that substance. So if two different substances are one mole each, they contain the same number of atoms.

The atomic masses of the given substances are as follows: O = 16, H = 1, CO₂ = 44, N = 14, C = 12, Na = 23.

The number of atoms present in each mass is given by the formula

For option (i), No. of oxygen atoms = x 6.023 x 10²³

No. of hydrogen atoms = x 6.023 x 10²³

(ii) No. of oxygen atoms = x 6.023 x 10²³

No. of carbon dioxide atoms = x 6.023 x 10²³

(iii) No. of nitrogen atoms = x 6.023 x 10²³

No. of oxygen atoms = x 6.023 x 10²³

D. No. of carbon atoms = x 6.023 x 10²³

No. of sodium atoms = x 6.023 x 10²³

According to the calculation, the correct answers are (ii), (iii), and (iv).