Question

150gram of NaoH were dissolve in 250cm³ of a solution. Calculate the volume of 0.10m of HCl which would be neutralize by 20cm³ of alkali

Answer 1

One thing you need to learn early on is that M stands for molarity and m stands for molality. They are not the same thing. I will assume you meant 0.10 M and not 0.10 m.
150 g NaOH dissolved in 250 cc H2O is 150 x (1000/250) = 150 x 4 = 600 g NaOH/1000 cc or 600 g/L. What is the molarity? That is mol NaOH = grams/molar mass = 600/40 = 15 M
mols NaOH in 20 cc = M x L = 15 x 0.02 = 0.3
That will take 0.3 mol HCl.
M HCl = mols/L
0.1 = 0.3/L. Solve for L.