This happens because the cation of a strong base is a insignificant acid, and the anion of a weak acid is a weak base. Therefore, the stronger ion is a base: Basic solution. Example: $NaOCl$: $Na^+$: Cation of $NaOH$: Strong base $-\gt$ Insignificant acid. $OCl^-$: Anion of $HOCl$: Weak acid $-\gt$ Weak base. So, the solution is acidic.
Work Step by Step
Based on the principle: - "The stronger the acid/base, the weaker its conjugate base/acid." Therefore, comparing the $K_a$ and $K_b$ of the acid and base of the ions, if the base is stronger, the acid will be weaker. Weaker acid $ -\gt$ Stronger conjugate base. With a stronger conjugate base: Basic solution