Answer:
           Option-B (60%) is the correct answer.
Explanation:
           To solve this problem first we will calculate the mass of hydrated compound as,
Hydrated Compound  =  Mass of Anhydrous Compound + Mass of Hydrate
Hydrated Compound   =  3.0 g + 5.0 g
Hydrated Compound  =  8.0 g
Secondly, we will apply following formula to find percent of water in hydrated compound,
      %H₂O  =  Mass of H₂O / Mass of Hydrated Compound × 100
Putting values,
                    %H₂O  =  5.0 g / 8.0 g × 100
                      %H₂O =  62.5 % ≈ 60%
