Given, mass of CuSO₄ . 5H₂O = 80 g

The concentration of copper sulphate solution is x 10

$$-$$

3 mol/L.

Molarity = ..... (i)

Molar mass of CuSO₄ . 5H₂O = 63.54 + 32 + 16 4

= 5 18 = 249.54 g/mol

Number of moles of solute =

= = 0.32 mol

Volume of solution = 5 L

From Eq. (i),

Molarity = = 64.11 10

$$-$$

3 mol/L

x = 64.11

or x 64

Hence, answer is 64.