Density of a 2.05 M solution of acetic acid in water is 1.02 gm/ml. The molality of the solution is:

Molarity of acidic acid =2.05M        Let us consider a 1000 ml solution.        Number of moles of acetic acid per one litre of solution =2.05        Mass of acetic acid = number of moles gram molecular weight                                       =2.0560=123g        Mass of solution =density of solution  volume of solute                                      =1.02 1000=1020g        Mass of solvent = mass of solution – mass of solute                                      =1020-123=897g=0.897kg∴molality=number of moles of soluteweight of solvent in kg                        =2.050.897=2.28 moles/kg