The ionisation constant of an acid, Ka is the measure of strength of an acid. The Ka values of acetic acid, hypochlorous acid and formic acid are 1.74 x 10-5, 3.0 x 10- 8 and 1.8 x 10- 4, respectively. Which of the following orders of pH of 0.1 mol dm- 3 solutions of these acids is correct?