A student prepares a 0.050 mol dm-3 aqueous solution of methanoic acid (HCOOH\text{HCOOH}HCOOH) at 298 K.
At this temperature, the acid dissociation constant, KaK_{\text{a}}Ka, for methanoic acid is 1.80 × 10-4 mol dm-3.
Calculate the percentage of methanoic acid molecules that are dissociated in this solution. Show your working and give your answer to two significant figures.