To solve this problem, we can use the concept of stoichiometry and the equation:moles of acid = moles of baseSince the reaction between sodium hydroxide NaOH and hydrochloric acid HCl is a 1:1 reaction, we can write the equation as:moles of HCl = moles of NaOHWe are given the volume and concentration of HCl, so we can calculate the moles of HCl:moles of HCl = volume of HCl in L concentration of HCl in mol/L moles of HCl = 0.025 L 0.1 mol/L = 0.0025 molNow we know the moles of NaOH, which is equal to the moles of HCl:moles of NaOH = 0.0025 molTo find the concentration of NaOH, we can use the formula:concentration of NaOH in mol/L = moles of NaOH / volume of NaOH in L The volume of NaOH is given as 30 mL, which is equal to 0.03 L. Now we can calculate the concentration of NaOH:concentration of NaOH = 0.0025 mol / 0.03 L = 0.0833 mol/LTherefore, the concentration of the sodium hydroxide NaOH solution is approximately 0.0833 M.