Final answer:
A solution with no Ka value is classified as a strong acid or a strong base, with strong acids being the usual context when Ka is referenced since they ionize almost completely in water.
Step-by-step explanation:
A solution where there is no Ka value implies that the substance is a strong acid or a strong base, which almost completely ionizes in water. Weak acids and weak bases, in contrast, ionize only slightly, which corresponds to a measurable Ka or Kb value (base-ionization constant). The strong acid or base essentially has a Ka or Kb larger than the range of values that can be measured, often taken as effectively infinite compared to those of weak acids and bases. Therefore, to answer the question, if there is no Ka value, the solution can be classified as either a strong acid or a strong base. For acids, the lack of a Ka value typically indicates a strong acid.