Question

Which transition element among the following shows the highest number of oxidation states?

• A. Scandium (Sc)
• B. Iron (Fe)
• C. Manganese (Mn)
• D. Zinc (Zn)

Hint:

Transition Metal with Maximum Oxidation States: Manganese ($Mn$) can exhibit oxidation states from +2 to +7. The highest oxidation state in the first transition series is +7 (seen in $KMnO_4$).

Answer 1

The Correct Option is C

Concept: Transition elements show variable oxidation states because both their $ns$ and $(n-1)d$ electrons can participate in bonding. This allows them to exhibit multiple oxidation numbers. Among transition elements, the number of oxidation states generally increases toward the middle of the transition series.

Step 1: Electronic configuration of manganese. Manganese ($Z = 25$) has the electronic configuration: \[ [Ar]\,3d^5\,4s^2 \] Because it has five $d$ electrons and two $s$ electrons, a total of seven electrons can potentially participate in bonding.

Step 2: Possible oxidation states. Manganese commonly shows the following oxidation states: \[ +2,\ +3,\ +4,\ +5,\ +6,\ +7 \] Examples include:
• $Mn^{2+}$ in $MnCl_2$
• $Mn^{4+}$ in $MnO_2$
• $Mn^{7+}$ in $KMnO_4$

Step 3: Compare with other options.
• Scandium → Mainly shows +3 oxidation state.
• Iron → Commonly +2 and +3.
• Zinc → Only +2 oxidation state (due to fully filled $3d^{10}$ configuration). Therefore, among the given elements, manganese shows the highest number of oxidation states.