The oxidation potential of transition elements are lower than the oxidation potential of the s-block elements because

The ionization energy of the transition elements is higher than that of the corresponding s-block elements

The correct answer is option (2) The ionization energy of the transition elements is higher than that of the corresponding s-block elements.

The ionization energy of the transition elements is higher than that of the corresponding s-block elements.

The oxidation potential of an element is the tendency of that element to lose electrons. The higher the ionization energy, the more difficult it is for an element to lose electrons, and therefore the lower its oxidation potential.

The ionization energy of the transition elements is higher than that of the corresponding s-block elements because the transition elements have a partially filled d subshell. This subshell is relatively stable, and it takes more energy to remove an electron from it.

As a result, the oxidation potential of the transition elements is lower than the oxidation potential of the s-block elements.

The other options are incorrect.

Option (1): The hydration energy of transition metal cations is high. This means that transition metal cations are more likely to be hydrated, which can stabilize them and make them less likely to lose electrons. However, this does not explain why the oxidation potential of transition elements is lower than the oxidation potential of the s-block elements.

Option (3): The ionization energy of transition elements is lower than that of the corresponding s-block elements. This is incorrect. The ionization energy of the transition elements is higher than that of the corresponding s-block elements.

Option (4): The melting points of s-block elements are low. This is not relevant to the question of oxidation potential.