Which of the following statements concerning transition elements is false?

Options

A. They are all metals.
B. They easily form coordination compounds.
C. Their ions are mostly coloured.
D. They show multiple oxidation states always differing by two units.

Answer

To determine which statement concerning transition elements is false, let's analyze each option step by step:

1. **All transition elements are metals.**
- Transition elements are defined as the d-block elements in the periodic table. All d-block elements are indeed metals. Therefore, this statement is **true**.

2. **They easily form coordinate compounds.**
- Transition metals have vacant d-orbitals that can accept lone pairs from ligands, allowing them to form coordinate bonds. This property is characteristic of transition metals. Thus, this statement is also **true**.

3. **Their ions are mostly colored.**
- The color of transition metal ions is due to electronic transitions between d-orbitals. When light hits these ions, electrons can be excited from one d-orbital to another, leading to the absorption of certain wavelengths of light and the appearance of color. Hence, this statement is **true**.

4. **They show multiple oxidation states always differing by two units.**
- While transition metals do exhibit multiple oxidation states, they do not always differ by two units. For example, iron can exist in +2 and +3 oxidation states, but vanadium can have oxidation states of +5, +4, +3, +2, and +1, which do not follow the two-unit difference rule. Therefore, this statement is **false**.

Based on the analysis, the false statement is: **"They show multiple oxidation states always differing by two units."**