Question

Suppose you drink 90ml of water. How many molecules of water will enter your stomach?

Answer 1

Density of water = 1gm/mL

Therefore mass of 90 mL water = 90 gm

No. of molecules in 18 gm of water

= 6.022 * 10^23

Answer 2

Here's what you are looking for,

22.4 L (or 22400 ml) of water consists of 1 mole of water or simply 6.022 x 10^23 molecules of water.

Therefore, 90 ml of water consists = (90 x 6.022 x 10^23) / 22400

                                                          = 0.024 x 10^23 molecules