9.17 mL
In this question we are given;
NaOH(aq) + HCl(aq) → H2O(l) + NaCl(aq)
We are required to determine the volume of the alkali, NaOH used;
Molarity = Number of moles ÷ Volume
Thus, rearranging the formula;
Moles = Molarity × volume
= 0.055 M × 0.025 L
= 0.001375 moles
Therefore;
Hence; Moles of NaOH = 0.001375 moles
Molarity = Moles ÷ Volume
Volume = Moles ÷ Molarity
Therefore;
Volume of NaOH = 0.001375 moles ÷ 0.150 M
= 0.00917 L, but, 1 L = 1000 mL
= 9.17 mL
Therefore, the volume of NaOH required is 9.17 mL