Elements of which block generally show maximum variation in valency?

Options

A. p-block elements
B. s-block elements
C. d-block elements
D. d and s-block elements

Answer

To determine which block of elements generally shows the maximum variation in valency, we can analyze the characteristics of different blocks in the periodic table.

### Step-by-Step Solution:

1. **Identify the Blocks of Elements**:
- The periodic table is divided into four main blocks: s-block, p-block, d-block, and f-block.
- Each block corresponds to the type of atomic orbitals that are being filled with electrons.

2. **Understand Valency**:
- Valency refers to the ability of an atom to bond with other atoms, which is often determined by the number of electrons in the outer shell.
- Elements can exhibit different valencies based on their electronic configuration and the availability of electrons for bonding.

3. **Analyze the s-block Elements**:
- S-block elements (alkali and alkaline earth metals) typically have a fixed valency.
- For example, alkali metals have a valency of +1, and alkaline earth metals have a valency of +2.
- Thus, they do not show much variation in valency.

4. **Analyze the p-block Elements**:
- P-block elements can show some variation in valency, but it is limited compared to d-block elements.
- For instance, elements like carbon can exhibit a valency of +4 or -4, but this is not as extensive as that of d-block elements.

5. **Analyze the d-block Elements**:
- D-block elements, also known as transition metals, have partially filled d-orbitals.
- The presence of vacant d-orbitals allows these elements to lose different numbers of electrons, resulting in multiple oxidation states.
- For example, titanium can exhibit oxidation states of +2, +3, and +4, while manganese can show oxidation states ranging from +2 to +7.

6. **Conclusion**:
- Based on the analysis, d-block elements exhibit the maximum variation in valency due to their ability to utilize d-orbitals for bonding.
- Therefore, the answer to the question is that **d-block elements** generally show maximum variation in valency.

### Final Answer:
**D-block elements** show the maximum variation in valency.