Answer:
[tex]28.75\ \text{mL}[/tex]
Explanation:
[tex]C_1[/tex] = Initial concentration = 2 M
[tex]C_2[/tex] = Final concentration = 0.23 M
[tex]V_1[/tex] = Initial volume
[tex]V_2[/tex] = Final volume = 250 mL
We have the relation
[tex]C_1V_1=C_2V_2\\\Rightarrow V_1=\dfrac{C_2V_2}{C_1}\\\Rightarrow V_1=\dfrac{0.23\times 250}{2}\\\Rightarrow V_1=28.75\ \text{mL}[/tex]
So, the required volume is [tex]28.75\ \text{mL}[/tex].