The density of 3 M solution of NaCl is 1.25 g mL–1. Calculate the molalityof the solution.


Correct option is

2.79 m


3 M NaCl solution meants that 3 moles of NaCl are present in 1 L of the solution.

 Mass of 1 L, i.e., 1000mL of the solution



Mass of 3 moles of solute (NaCl)

                                     = 1074.5  g = 1.0745 kg

                                                    = 2.79 mol kg–1 = 2.79 m 




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