The first step to answer this question is to convert the volume of solution needed, that is in liters, to mililiters.
[tex]0.1L\cdot\frac{1000mL}{L}=100mL[/tex]
Use the concentration of the solution to find how many mg are present in 100mL of the solution:
[tex]100mL\cdot\frac{10mg}{mL}=1000mg[/tex]
Now, convert the amount of mg present in the solution to grams:
[tex]1000mg\cdot\frac{1g}{1000mg}=1g[/tex]
It means that 1g of NaOH is needed to prepare 0.1L of a 10mg/mL solution.
