JAMB Chemistry 2016 Paper

Concept:Neutralization produces a neutral salt and water, so litmus shows its neutral colour.Explanation:When HCl reacts with NaOH, the acid and base completely neutralize each other.The equation is: $\mathrm{HCl (aq) + NaOH (aq) \rightarrow NaCl (aq) + H_2O (l)}$At the end point, neither excess acid nor excess base remains.The solution is exactly neutral, with pH $7$.Litmus is a natural indicator that shows different colours in different media.In acidic solution, litmus turns red.In alkaline solution, litmus turns blue.In a neutral solution, like the salt solution formed here, litmus remains purple.Therefore, the colour observed at the end point is purple.Answer:D. Purple