Expert's please answer the question

Dear Student,

First of all i think that here is a typing error it should be molality instead of molarity. Now solution of your problem is given as under:

Molality  = moles of the solute/ weight of the solvent (in kg)

Mole fraction of ethanol that is X= 0.040

Ethanol is a solute.

X_ethanol = n_ethanol  / (n_ethanol +n_H20)

As molality of the solution is to be calculated, therefore amount of water to be  taken =  1 kg = 1000 g

 n_H20  =  1000/18 =55.55 moles

Hence 0.040  = n_ethanol  / (n_ethanol +55.55)

From here we get  n_ethanol   = 2.314

Hence molality = 2.314