#5. The probability that you in any glass of water will find at least 1 molecule of H2O once drunk by Cleopatra is practically 100%
Similarly the chance is close to 100% in the example with the glass of H2O because there are much more molecules of water in a glass than there are glasses of h2O in the total amount of h2O on the planet.
The atomic mass of hydrogen is 1.00784 u and that of oxygen is 15.9994 u. Therefore, the molecular mass of water with formula H2O is (2 × 1.00784 u) + 15.9994 u = 18.01508 u. Therefore, one molecule of H2O weighs 18.01508 u, and one mole of water weighs 18.01508 grams. Source: mathematics.bigparadox.com