What mass of solute is present in 250. mL of a 0.100 mol/L solution of NaOH?
There will be 1.00 g of NaOH in the solution.
In dealing with solution Chemistry, there is a relation that you must know and understand - to find the number of moles of solute in a solution, you multiply the molar concentration of the solution times its volume in litres.
Once that is done, you convert moles to mass by multiplying by the molar mass of the solute.
In this case:
moles NaOH =
To find mass: