Answer
6.022 x 10$^{23}$
Work Step by Step
As the density of water is 1 $\frac{gram}{milliliter}$, 18 mL of water is equal to 18 grams. Thus, the given mass is 18 grams.
Molecular Mass of H$_{2}$O = (16+2) x 1 = 18 grams
Number of Moles = $\frac{Given Mass}{Molecular Mass}$
Number of Moles = $\frac{18}{18}$
Number of Moles =1
We can now calculate the number of molecules using this formula:
Number of Molecules = Number of Moles x Avogadro Number
Number of Molecules = 1 x 6.022 x 10$^{23}$
Numer of Molecules = 6.022 x 10$^{23}$
