Answer:
We know the initial volume of the potassium nitrate solution is 1.0 mL and the initial concentration is 2.0 M, we also know that an unknown volume of water was added to the solution, which diluted our concentration down to a final value of 0.008 M. We are trying to find the final volume.
Here we can use this formula since the initial and final solutions are proportional. Before that let's define our variables.
[tex]M_1 = 2.0 M\\V_1 = \frac{1.0 mL}{1000} = 0.001 L\\M_2 = 0.008 M\\V_2 = \ ?[/tex]
[tex]M_{1}V_{1} =M_2 V_2\\[/tex]
[tex](2.0)(0.001) = (0.008)V_2\\\\\frac{(2.0)(0.001)}{0.008} = V_2\\\\V_2 = 0.25 L \ or \ (0.25 \ * \ 1000) = 250 \ mL[/tex]
Therefore you would have 0.25 L or 250 mL of your final solution.