Mass of CuSO₄.5H₂0 = 6.25 g (B)
MW CuSO₄.5H₂0 =250 g/ mol
mol of CuSO₄
[tex]\tt 0.25\times 0.1=0.025[/tex]
mass of CuSO₄ (MW=159.61 g/mol)
[tex]\tt 0.025\times 159.61=3.99~g[/tex]
[tex]\tt mass~CuSO_4=\dfrac{159.61}{250}\times mass~CuSO_4.5H_2O\\\\mass~CuSO_4.5H_2O=\dfrac{3.99\times 250}{159.61}=6.25~g[/tex]