This is for chem and i don't understand:
a snowflake contains 2.0*10^18 molecules of water. how many moles of water does it contain?

Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles. We calculate as follows:

 2.0*10^18 molecules of water ( 1 mol / 6.022 x 10^23 molecules ) = 3.32x10^-6 mol water

Sorry i dont understand the question can you rephase it?