Astock solution is made by dissolving 66.05 g of (nh4)2so4 in enough water to make 250 ml of solution. a 10.0 ml sample of this solution is then diluted to 50.0 ml. given that the molar mass of (nh4)2so4 is 132.1 g/mol, what is the concentration of the new solution?

If the solute is properly distributed in the given volume, there are 2.642 g of (NH4)2SO4 per 10 mL. For the new solution, divide the 2.642 g by the molar mass of the compound. The answer is 0.02 moles. Then, divide this by the new volume, 50 mL or 0.05 L. The concentration of the new solution is 0.4 M. 

The answer is 4 i don't know if its right let me see.