d block elements mostly form

Options

A. coloured ions
B. colourless ions
C. white coloured ions
D. none of the above

Answer

**Step-by-Step Solution:**

1. **Understanding D-Block Elements:**
- D-Block elements are those elements in which the last electron enters the d-orbital. These elements are found in groups 3 to 12 of the periodic table.

2. **Formation of Colored Ions:**
- D-Block elements typically form colored ions. This is due to the presence of unpaired electrons in their d-orbitals.

3. **Presence of Unpaired Electrons:**
- The color in these compounds arises from the presence of unpaired electrons. When an electron is unpaired, it can be involved in electronic transitions that result in the absorption of certain wavelengths of light, leading to the appearance of color.

4. **Paramagnetism:**
- Compounds with unpaired electrons are paramagnetic, which means they are attracted to magnetic fields. This property is often observed in colored complexes of d-block elements.

5. **Example of Titanium Complex:**
- For instance, consider the titanium ion in the complex [Ti(H2O)6]³⁺. In this case, titanium has a +3 oxidation state, resulting in an electron configuration of [Ar] 3d¹. This means there is one unpaired electron.

6. **D-D Transitions:**
- The color observed in these complexes is due to d-d transitions, where an electron jumps from a lower energy d-orbital to a higher energy d-orbital. This transition absorbs specific wavelengths of light, and the remaining wavelengths are what we perceive as color.

7. **Conclusion:**
- Therefore, the primary characteristic of d-block elements is that they mostly form colored ions due to the presence of unpaired electrons and the resulting d-d transitions.

**Final Answer:**
D-Block elements mostly form colored ions.

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