One mole of H2O means:
i. 18 g of H2O
ii. 6.022 x 1023 molecules of H2O
iii. 180 g of H2O
iv. 1.8 of H2O
18 g of H2O:
⇒
⇒ Number of moles = 1
6.022 x 1023 molecules of H2O:
We now that 1 mole contains 6.022 x 1023 molecules.
Thus, option A is correct.