The acidic order is due to increase in bond length(decrease in bond energy) and same reason for thermal stability
So acidity increases means O-H bond strength decreases so thermal stability should decrease
Acidic strength order is coz of oxidation state of central atom
And thermal stability?
I guess we can explain thermodynamically. More number CO bonds..
Its just a way to remember acidic strenght. When you valculate bond order in Cl-OH bond, BO decreases as we ON increase. So s character in Cl-OH bond increase and thus s character in O-H bond decrease which makes them longer and weaker
I just gave that ON trend for remembering but it can also be explained in the following way. Consider the conjugate bases, more canonical forms. Therefore, most stable is HOClO3’s conjugate base.