Asolution contain 16g of urea in 120g of solution. What is mass by mass percentage of solution .

The concentration of a solution in terms of mass by mass percentage is given as 

 mass by mass percentage = (mass of solute / mass of solution) X 100

Here mass of the solute =  mass of urea = 16g  (given)

mass of solution = mass of solute + mass of solvent = 120 g  (given)

Therefore mass by mass percentage of solution = (16 / 120) X 100 = 13.333 %

Thus the mass percentage of the solution is 13.333 %.