22) B

Mr of hydrated copper (II) sulfate = (64) + (32) + (16 x 4) + (10 x 1) + (16 x 5) = 250
Mass of hydrated copper (II) sulfate = 10 g

Moles = Mass / Mr = 10 / 250 = 0.04 mol

We know moles = concentration x volume
We have the volume as 100 cm³. This is equal to 0.1 dm³

Moles = concentration x volume
Concentration = Moles / volume
Concentration = (0.04 ÷ 0.1) = 0.4 mol/dm³