The least stable hydride is

Options

A. Staanane
B. Silane
C. Plumbane
D. Germane

Explanation

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

### Step 1: Identify the Elements and Their Hydrides
- The hydrides in question are derived from elements in Group 14 of the periodic table.
- The elements and their corresponding hydrides are:
- Silane (SiH4) from Silicon (Si)
- Germane (GeH4) from Germanium (Ge)
- Stannane (SnH4) from Tin (Sn)
- Plumbane (PbH4) from Lead (Pb)

### Step 2: Understand the Trend in Stability of Hydrides
- As we move down the group in the periodic table from Si to Pb, the size of the central atom increases.
- This increase in atomic size leads to an increase in the bond length between the central atom and hydrogen.

### Step 3: Analyze the Effect of Bond Length on Stability
- Longer bond lengths generally result in weaker bonds. Therefore, as the bond length increases, the energy required to break the bond decreases, leading to decreased stability of the hydride.
- Thus, the stability of the hydrides decreases as we move down the group: SiH4 > GeH4 > SnH4 > PbH4.

### Step 4: Identify the Least Stable Hydride
- Based on the trend, plumbane (PbH4), which is derived from the largest atom (Lead), will have the weakest bond and thus be the least stable hydride.

### Conclusion
- Therefore, the least stable hydride among the given options is **plumbane (PbH4)**.

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

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