NEET Chemistry (general) MCQ Question
Which of the following statements about the standard electrode potentials of transition metals is correct?
The E° value for Mn3+/Mn2+ is much more positive than for Cr3+/Cr2+ due to a larger third ionisation energy.
Cu has a negative E° value, allowing it to liberate H2 from acids.
The E° values for all transition metals increase sequentially without irregularities.
The hydration enthalpy of Cu2+ ions is significantly higher than the ionisation enthalpy of Cu.
Correct Answer
Detailed Explanation
The higher third ionisation energy of Mn, resulting in a transition from d5 to d4 configuration, explains why the E° value for Mn3+/Mn2+ is much more positive compared to Cr3+/Cr2+ and Fe3+/Fe2+. This irregularity is not seen in other pairs due to the unique electronic configuration of Mn.
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