molarity is defined as the number of moles of solute in 1 L of solution
number of NaOH moles present - 0.20 mol
volume of solution - 150 mL
since molarity is taken as number moles of solute in 1000 mL
if 150 mL contains - 0.20 mol
then 1000 mL should contain - 0.20 / 150 x 1000 = 1.33 mol
therefore molarity is 1.33 M
