How many moles of water, h2o, contain 2.0×1022 molecules of water? (see the hints for assistance in interpreting scientific notation.)
express the quantity in moles to two significant figures.

Scientific notation is the standardized way to represent any number as the product of a real number and a power of ten. Apply Avogadro's constant which is 6.023x10^23 molecules per mole.

20x10^22 molecules / 6.023x10^23 molecules per mole = 0.33 moles.