Taking into account the definition of dilution, the concentration of the final solution is 5 mg/L.
First of all, you have to know that dilution is the reduction in concentration of a chemical in a solution. The process consists of adding more solvent to the same amount of solute.
In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases.
A dilution is mathematically expressed as:
Ci×Vi = Cf×Vf
where
In this case, you know:
Replacing in the definition of dilution:
25 mg/L × 10 mL= Cf × 50 mL
Solving:
Cf= (25 mg/L × 10 mL)÷ 50 mL
Cf= 5 mg/L
In summary, the concentration of the final solution is 5 mg/L.
Learn more about dilution: