Least stable hydride is

Options

A. stannane
B. silane
C. plumbane
D. germane

Explanation

To determine the least stable hydride among stane (SnH4), silane (SiH4), plumbane (PbH4), and germane (GeH4), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Hydrides**:
- Stane (SnH4) - Hydride of Tin
- Silane (SiH4) - Hydride of Silicon
- Plumbane (PbH4) - Hydride of Lead
- Germane (GeH4) - Hydride of Germanium

2. **Understand the Trend in Stability**:
- The stability of hydrides generally decreases as we move down a group in the periodic table. This is due to the increase in atomic size and the corresponding increase in bond length.

3. **Analyze the M-H Bond**:
- As we go from SiH4 to PbH4, the size of the central atom (M) increases:
- Si (Silicon) < Ge (Germanium) < Sn (Tin) < Pb (Lead)
- The bond length of M-H increases, leading to weaker M-H bonds.

4. **Determine the Stability**:
- Since the M-H bond becomes weaker as the size of M increases, the stability of the hydrides decreases in the order:
- SiH4 > GeH4 > SnH4 > PbH4
- Therefore, PbH4 (plumbane) will be the least stable hydride among the given options.

5. **Conclusion**:
- The least stable hydride is **Plumbane (PbH4)**.

### Final Answer:
The least stable hydride is **Plumbane (PbH4)**.

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