**Step-by-Step Solution:**
1. **Understanding Variable Valency:**
- Variable valency refers to the ability of an element to exhibit different oxidation states. This means that an element can lose or gain different numbers of electrons, resulting in various charges.
2. **Identifying Transition Elements:**
- Transition elements are found in the d-block of the periodic table. These elements typically have partially filled d-orbitals, which allow them to lose different numbers of electrons and exhibit variable valency.
3. **Examples of Transition Elements:**
- Common transition elements include Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), and Zinc (Zn).
- For instance, Scandium can have oxidation states of +1 and +3, while Chromium can have oxidation states of +2, +3, +6, etc.
4. **General Electron Configuration:**
- The general electron configuration for transition elements can be represented as \(ns^2 (n-1)d^{1-10}\), where 'n' is the principal quantum number. This configuration indicates that the last electrons enter the d-subshell.
5. **Variable Oxidation States:**
- Transition elements can exhibit a range of oxidation states. For example:
- Titanium can have +2 and +4.
- Vanadium can have +2, +3, +4, and +5.
- Manganese can have +2, +4, +6, and +7.
- This variability is due to the involvement of both the s and d electrons in bonding.
6. **Conclusion:**
- Therefore, the characteristic of variable valency is primarily associated with transition elements due to their ability to have multiple oxidation states.
**Final Answer:**
Variable valency is characteristic of transition elements.
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