how would you prepare 250 ml of 0.69m al2(so4)3 solution from a 2.0 al2(so4)3 stock solution

Answer 1

2.0 what? m
Is that 0.69m or 0.69M? I assume 0.69m
That means 0.69 mol/0.250 kg solvent.
0.69 x molar mass Al2(SO4)3 = approx 60g.
Then the solvent has a mass of 250 g for a total mass of approx 250+60 = approx 0310 g. What's the density of the solution? volume = mass/density = ? = approx 310 mL or 0.310 L.
Then use c1v1 = c2v2.