If ${\text{20 c}}{{\text{m}}^{\text{3}}}$ samples of ${\text{0.1 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}$ solutions of the acids below are taken, which acid would require a different volume of ${\text{0.1 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}$ sodium hydroxide for complete neutralization?

A.     Nitric acid

B.     Sulfuric acid

C.     Ethanoic acid

D.     Hydrochloric acid

B

This question on the neutralization of an alkali by various acids proved to be a particularly good discriminator (Discrimination Index 0.68), with many of the weaker students considering that the strength of the acid would affect the amount required.