Though a transition element, scandium (Z = 21) does not exhibit variable oxidation state.

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Transition Elements**: Transition elements are defined as d-block elements that have partially filled d-orbitals in at least one of their oxidation states. They typically exhibit variable oxidation states due to the involvement of d-electrons in bonding.

2. **Identifying Scandium**: Scandium (Sc) has an atomic number of 21. Its electron configuration is [Ar] 3d¹ 4s². In its ground state, scandium has one electron in the 3d subshell and two electrons in the 4s subshell.

3. **Oxidation States of Scandium**: The most common oxidation state of scandium is +3. This occurs when scandium loses its two 4s electrons and one 3d electron, resulting in the configuration [Ar] 3d⁰. Scandium does not exhibit other oxidation states like many other transition metals do.

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