Explanation:

HClO4 is a strong acid and will completely dissociate in water to form H+ and ClO4- ions. CH3OH is a polar molecule but not an acid and will not dissociate in water. KBr is a salt and will dissociate in water to form K+ and Br- ions. HCl is a strong acid and will completely dissociate in water to form H+ and Cl- ions.