A 4 M solution of lithium bromide has to be made with 100 grams of lithium bromide. A solution with a concentration of 1 M has one mole of the solute dissolved in one liter of the solution.
The molecular mass of lithium bromide is 86.845 g/mole. 100 grams of lithium bromide make up 100/86.845 moles or 1.151 moles.
A 4 M solution of lithium bromide requires 4 moles of the compound per liter. As we only have 1.51 moles with us, the volume of 4 M solution that can be made is given by 1.51/4 L or 0.2878 L.
It is possible to make 0.2878 liters of 4 M solution of lithium bromide using 100 grams of the compound.