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Using the following standard reduction potentials: E°(Sc^3+/Sc) = −0.37, E°(Mn^3+/Mn^2+) = +1.57, E°(Cr^2+/Cr) = −0.90, E°(Cu^2+/Cu) = +0.34, which statement is not correct?

1. Sc^3+ is highly stable because it has the [Ar]3d^0 4s^0 arrangement.
2. Mn^3+ is more stable than Mn^2+.
3. Cr^2+ acts as a reducing agent.
4. Copper does not liberate H2 when treated with dilute H2SO4.

Correct answer: Sc^3+ is highly stable because it has the [Ar]3d^0 4s^0 arrangement.

Solution

Sc^3+ is not highly stable; rather, it is a strong oxidizing agent due to its empty d-orbitals, making it less stable than its elemental form. The electron configuration does not confer stability in this case.

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