In which of the following the inert pair effect is most prominent?

Options

A. C
B. GE
C. Si
D. Pb

Explanation

To determine in which of the given elements the inert pair effect is most prominent, we need to analyze the options provided: carbon, germanium, silicon, and lead.

### Step-by-Step Solution:

1. **Understanding the Inert Pair Effect**:
The inert pair effect refers to the tendency of the outermost s-electrons (the "inert pair") to remain non-bonding or unshared in heavier elements of a group in the periodic table. This effect becomes more pronounced as we move down a group.

2. **Identifying the Elements**:
- **Carbon (C)**: Group 14, period 2
- **Silicon (Si)**: Group 14, period 3
- **Germanium (Ge)**: Group 14, period 4
- **Lead (Pb)**: Group 14, period 6

3. **Trend in the Group**:
As we move down the group from carbon to lead, the size of the atoms increases, and the effective nuclear charge experienced by the outermost electrons decreases. This leads to a greater tendency for the s-electrons to remain non-bonding.

4. **Analyzing Lead**:
Lead (Pb), being the heaviest in the group, shows a significant inert pair effect. In lead, the s-electrons (6s) are less likely to participate in bonding compared to the p-electrons, resulting in lead commonly exhibiting a +2 oxidation state rather than a +4 oxidation state.

5. **Conclusion**:
Among the options provided, the inert pair effect is most prominent in lead (Pb). This is evidenced by its stability in the +2 oxidation state compared to the +4 state.

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

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