The inert pair effect is most prominent in

Options

A. C
B. Pb
C. Ge
D. Si

Answer

To determine where the inert pair effect is most prominent, we need to analyze the elements provided in the options: carbon (C), lead (Pb), germanium (Ge), and silicon (Si).

### Step-by-Step Solution:

1. **Understanding the Inert Pair Effect**:
- The inert pair effect refers to the tendency of the outermost s-electrons (ns²) to remain non-bonding or "inert" in heavier elements of a group, particularly in the p-block elements.

2. **Identifying the Group**:
- Carbon (C) is in Group 14, silicon (Si) is also in Group 14, germanium (Ge) is in Group 14, and lead (Pb) is in Group 14 as well.

3. **Position in the Periodic Table**:
- As we move down the group from carbon to lead, the atomic size increases due to the addition of electron shells. This increase in size affects the bonding characteristics of the elements.

4. **Effect of Screening**:
- The screening effect becomes more significant as we move down the group. The inner d and f orbitals provide shielding, which reduces the effective nuclear charge felt by the outermost s-electrons.

5. **Analyzing Lead (Pb)**:
- Lead (Pb), being the heaviest among the options, experiences the most significant inert pair effect. The ns² electrons (in this case, 6s²) are less likely to participate in bonding due to the increased shielding from the filled inner f orbitals.

6. **Conclusion**:
- Therefore, the inert pair effect is most prominent in lead (Pb) compared to carbon, silicon, and germanium.

### Final Answer:
The inert pair effect is most prominent in lead (Pb).