Question

How many moles of molecules are in 40g of H2O?

Answer 1

Molecular mass of H2O is: 16+2*1=18
so moles of 40g of H2O is: 40/18=2.22

Answer 2

The question seems to be confusing but what I understood is that we are asked the number of moles for 40 g of H2O. The molar mass of H2O is the some of the atomic masses of the elements involved which would be 18.02 g/mol

40 g H2O ( 1 mol / 18.02 g ) = 2.22 mol H2O

Hope this answers the question. Have a nice day.