Final answer:
Among the given options, HClO₄ will have the strongest conjugate base.
Step-by-step explanation:
In general, the strength of a conjugate base is determined by the strength of its acid. The stronger the acid, the weaker its conjugate base, and vice versa. In this case, we need to compare the strengths of the acids: HClO₄, HClO₃, HClO₂, and HClO.
Out of the given options, HClO₄ is the strongest acid because it has the highest number of oxygen atoms bonded to the central chlorine atom. As a result, it will have the weakest conjugate base (ClO₄-).
Therefore, HClO₄ will have the strongest conjugate base among the given options.