Dear Student, Given, NaOH is 40% weight/volume i.e. 40 g of NaOH is present in 100 ml of solution. As density is 1 g/ml, so mass of solution = 100 g So, mass of NaOH = 40 g mass of water = 60 g Molar mass of NaOH = 40 g/mol Moles of NaOH = 40 g/40 = 1 mole Moles of water = 60/18 = 3.33 mole Regards