Calculate the mass of naoh needed to prepare 100. ml of 0.15m solution.

as, molarity = number of moles of solute / volume of solution (in liter)

here, volume is 500ml or 0.5 l

molarity is 0.04M

no. of moles of solute = mass of NaOH required (x) / gram atomic mass of NaOH (=40)

therefore, 0.04 = x / (40 x 0.5)

x = 0.8gram