vii. The stability of dihalides of ` Si, Ge , Sn` and Pb increases steadily in the sequence :

Options

A. `PbX_(2) lt lt SnX_(2) lt lt GeX_(2) lt lt SiX_(2)`
B. `GeX_(2) lt lt SiX_(2) lt lt SnX_(2) lt lt PbX_(2)`
C. `SiX_(2) lt lt GeX_(2) lt lt PbX_(2) lt lt SnX_(2)`
D. `SiX_(2) lt lt GeX_(2) lt lt SnX_(2) lt lt PbX_(2)`

Explanation

To determine the stability of the dihalides of silicon (Si), germanium (Ge), tin (Sn), and lead (Pb), we need to analyze the trend in stability as we move down the group in the periodic table. Here’s the step-by-step solution:

### Step 1: Understand the Group 14 Elements
Group 14 elements include carbon (C), silicon (Si), germanium (Ge), tin (Sn), and lead (Pb). We are focusing on the dihalides of Si, Ge, Sn, and Pb.

### Step 2: Identify the Dihalides
The dihalides of these elements can be represented as:
- SiX₂ (Silicon dihalide)
- GeX₂ (Germanium dihalide)
- SnX₂ (Tin dihalide)
- PbX₂ (Lead dihalide)

Where X represents a halogen.

### Step 3: Consider the Inert Pair Effect
The stability of these dihalides is influenced by the inert pair effect. The inert pair effect refers to the tendency of the s-electrons in the outermost shell to remain non-bonding as we move down the group. This effect becomes more pronounced in heavier elements.

### Step 4: Analyze Stability Trend
- **Silicon (Si)**: Si has a strong tendency to form covalent bonds and its dihalide (SiX₂) is relatively stable.
- **Germanium (Ge)**: Ge also forms stable dihalides, but the stability is slightly less than that of Si due to the inert pair effect starting to play a role.
- **Tin (Sn)**: Sn shows a further decrease in stability of its dihalides (SnX₂) as the inert pair effect becomes more significant.
- **Lead (Pb)**: Pb has the least stability for its dihalides (PbX₂) because the inert pair effect is very pronounced, leading to a preference for the +2 oxidation state over the +4 state.

### Step 5: Conclusion
Based on the analysis, the stability of the dihalides increases in the following order:
SiX₂ < GeX₂ < SnX₂ < PbX₂

Thus, the correct sequence of stability is:
**Si < Ge < Sn < Pb**

### Final Answer
The stability of dihalides of Si, Ge, Sn, and Pb increases steadily in the sequence: **Si < Ge < Sn < Pb**.

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