What volume of 0.5 mol dm−³ H2SO4 will exactly neutralize 20cm³ of 0.1 mol dm−³ NaOH solution?

A. 2.0 cm³
B. 5.0 cm³
C. 6.8 cm³
D. 8.3 cm³

Correct Answer:

Option A – 2.0 cm³

Explanation

2NaOH + H2SO4 → Na2SO4 + 2H2O
CaVa/CbVb = ratio of acid/ratio of base
(0.5 * Va)/(0.1 * 20) = 1/2
∴ Va = 2.0cm