There is 40 g of sugar in a 500 ml bottle of lemon juice
The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight/volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.
the concentration of sugar in lemon juice :
[tex]\tt \dfrac{20~g}{250~ml}=0.08~g/ml[/tex]
So for 500 ml juice :
[tex]\tt 500\times 0.08=40~g~sugar[/tex]