Question: how many moles of water are in one drop of liquid?
Answer: A drop of water is 0.05 mL of water, so its mass would be 0.05 grams. One mole of water is 18.016 grams, so in 0.05 grams, in one drop, the number of moles is: moles of water in one drop = 0.05 grams x (1 mole/18.016 grams) moles of water in one drop = 0.002775 moles.