molarity can be defined as the number of moles of solute in volume of 1 L solution
molarity of LiF is 0.880 M
the mass of LiF added is 25.5 g / 26 g/mol = 0.98 mol
the concentration of LiF that is to be prepared = 0.880 M
volume of 0.880 mol is 1 L
therefore volume that contains 0.98 mol - 0.98 mol / 0.880 mol/L
Volume of solution containing 25.5 g of LiF is - 1.11 L
therefore volume required is - 1.11 L