The addition of Sodium Hydroxide would primarily raise which parameter?

• A. Alkalinity
• B. pH
• C. Hardness
• D. Conductivity

Answer: (B)

Adding sodium hydroxide introduces hydroxide ions, which raise the solution’s basicity. The extra OH− neutralizes free hydrogen ions, pushing the hydrogen-ion activity downward and increasing the pH. pH is the direct readout of how acidic or basic a solution is, so it responds immediately to a strong base like NaOH.

Alkalinity would also rise because OH− contributes to the buffering capacity, but alkalinity is a buffering property tied to carbonate/bicarbonate species, so its change is not as immediate or straightforward as the pH change. Hardness would not be affected because it depends on calcium and magnesium ions, which sodium hydroxide does not introduce. Conductivity would rise due to the added ions, but the most direct and primary change from adding a strong base is the increase in pH.