hitunglah fraksi urea dalam larutan urea 20% Mr urea = 60

jawab; 20% urea = 20 gram urea dan 80 gram air
    X = mol urea/mol urea + mol air
       = 20/60 / 20/60+80/18
       = 0.33 / 0.33+4.44
       = 0.33 / 4.77
       = 0.069