Solution: We know that
Molarity of a solution = Number of moles of solute/Volume of solution in Litres
molar mass of C12H22O11 = 12*12. + 1*22 + 11*16 = 342 g / mol
number of moles of solute = mass of solute / molar mass of solute
= 20/342 = 0.0585 moles
molarity (M ) of the solution = 0.0585/2 = 0.0293 M