Oxidation Number And Oxidation States

To determine the correctness of the given statements, let's analyze each one individually:

1. Statement I: The higher oxidation states are more stable down the group among transition elements unlike p-block elements.
   • In the d-block (transition elements), the trend is generally observed that elements tend to show higher oxidation states as we move down the group. This happens due to the availability of more d orbitals which get increasingly involved in bonding as we move down a group, contributing to higher oxidation states.
   • For example, in Group 6, chromium shows a stable oxidation state of +6 in compounds like CrO₃, while tungsten (W) and molybdenum (Mo), which are below chromium in the periodic table, also exhibit +6 oxidation states in WO₃ and MoO₃, which are quite stable.
   • In contrast, for p-block elements, especially in groups like the nitrogen group, the higher oxidation states become less stable as we go down the group. For example, nitrogen exhibits a stable +5 oxidation state in N₂O₅, while bismuth in the same group predominantly shows the +3 oxidation state with the +5 state being less stable.
   • Hence, Statement I is true.
2. Statement II: Copper cannot liberate hydrogen from weak acids.
   • Copper is less reactive than hydrogen in the electrochemical series. Therefore, it does not easily displace hydrogen ions from acidic solutions, including weak acids, to liberate hydrogen gas.
   • This property is seen because copper will not react with the hydrogen ions without a higher impetus, which weak acids do not provide. Stronger acids like hydrochloric acid can oxidize copper in the presence of oxygen or another oxidizing agent rather than just displacing hydrogen.
   • Thus, Statement II is also true.

By reviewing both statements, it is clear that both Statement I and Statement II are true. Therefore, the correct answer is: Both Statement I and Statement II are true.