d and f BLOCK ELEMENTS

Which of the following best describes the stability gained when Cr2+ (d4) is oxidized to Cr3+ (d3)?

• Stabilization due to a fully filled d subshell.
• Stabilization due to a half-filled d subshell.
• Stabilization due to pairing of electrons in the eg level.
• Stabilization due to a half-filled t2g level in the d3 configuration.

What does a positive standard electrode potential (E°) for the Cu2+/Cu couple indicate about the spontaneity of the reaction Cu → Cu2+ + 2e-?

• The reaction is spontaneous.
• The reaction is at equilibrium.
• The spontaneity cannot be determined from E° alone.
• The reaction is non-spontaneous.

What is the relationship between the standard electrode potential (E°) and the ability of a metal to liberate H2 from acids?

• Metals with positive E° values can liberate H2, while those with negative E° values generally cannot.
• There is no relationship between E° and the ability to liberate H2.
• Only the hydration enthalpy determines the ability to liberate H2.
• Metals with negative E° values can liberate H2, while those with positive E° values generally cannot.

Why do Mn, Ni, and Zn have more negative E°(M2+/M) values than expected from the general trend?

• Because they have lower ionization enthalpies than their neighbors.
• Because they have higher hydration enthalpies than their neighbors.
• Because they are less abundant than their neighbors.
• Due to factors related to their specific electronic configurations leading to more stable M2+ ions or more favorable hydration.

What general trend is observed for the M2+/M standard electrode potentials across the first transition series (Sc to Zn)?

• A general trend towards more negative E° values across the series.
• A general trend towards increasingly positive E° values across the series.
• A general trend towards increasingly negative E° values across the series.
• A general trend towards less negative E° values across the series.