Transition metals are characterised by which of the following properties ?

Options

A. Fixed valency
B. coloured compound
C. high melting and boiling points
D. tendency to form coomplexes

Answer

To answer the question regarding the characteristics of transition metals, we will analyze each option provided and determine which properties are true for transition metals.

### Step-by-Step Solution:

1. **Understanding Transition Metals**:
Transition metals are elements found in the d-block of the periodic table. They are known for their unique properties due to the presence of d-electrons.

2. **Analyzing Each Option**:
- **Option 1: Fixed Valency**:
- Transition metals do not exhibit fixed valency. Instead, they show variable valency. For example, manganese can have oxidation states ranging from +2 to +7. Therefore, this option is **incorrect**.

- **Option 2: Colored Compounds**:
- Transition metals often form colored compounds. This is due to d-d electron transitions, where electrons absorb certain wavelengths of light and emit others, resulting in color. Therefore, this option is **correct**.

- **Option 3: High Melting and Boiling Points**:
- Transition metals typically have high melting and boiling points due to their strong metallic bonding and close-packed structure. Therefore, this option is **correct**.

- **Option 4: Tendency to Form Complexes**:
- Transition metals have a tendency to form coordination complexes. This is because they can accept electrons from ligands due to their variable valency. Therefore, this option is **correct**.

3. **Conclusion**:
Based on the analysis:
- Option 1 is incorrect.
- Options 2, 3, and 4 are correct.

### Final Answer:
Transition metals are characterized by:
- Colored compounds (Option 2)
- High melting and boiling points (Option 3)
- Tendency to form complexes (Option 4)