Final answer:
The acidity of oxyacids increases down a group on the periodic table as the number of terminal oxygen atoms attached to the central atom increases.
Step-by-step explanation:
The acidity of oxyacids increases down a group on the periodic table. This trend can be explained by the increase in the number of terminal oxygen atoms attached to the central atom, which increases the acidity of the compound. For example, as we move down the halogen group, the acidity of the oxyacids of chlorine increases from HClO to HClO2 to HClO3 to HClO4.