Answer :
First you have to figure out the atomic mass of each element(amu) then add them up to find your answer. we already know H2O is 55.5 g/mol. One Hydrogen molecule is 1.01 g/mol, A Carbon molecule is 12.01 g/mol, Oxygen molecule is 16.00 g/mol,Nitrogen molecule is 14.00, and a Sulfur molecule is 32.06 g/mol. Add those up you get 75.08 round to nearest whole number you get 75 g/mol are in a flask of water.