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.

In this question, what are we really being asked? We are being asked about the number of moles there in 2.0x10^22 molecules of H2O.

We are going to use the formula,

Number of moles = Number of molecules / Avogadro's number

We have the number of molecules: 2.0 x 10^22

Avogadro's number: 6.02 x 10^23

Now we will plug in our information in a scientific calculator:

(2.0 x 10^22) / (6.02 x 10^23) = 0.03 moles is our answer.