Soldiers of Napolean army while at alps during freezing winter suffered a serious problem as regards to the tin buttons of their uniforms. White metallic tin buttons got converted to grey powder. This transformation is related to

Options

A. a change in the partial pressure of oxygen in the air.
B. a change in the crystalline structure of tin.
C. an interaction with nitrogen of the air at very low temperatures.
D. an interaction with water vapours contained in the humid air

Explanation

**Step-by-Step Solution:**

1. **Understanding the Problem**: The question describes a situation where the tin buttons of Napoleon's army uniforms transformed from a white metallic form to a grey powder during freezing winter conditions. This transformation is a significant issue.

2. **Identifying the Forms of Tin**: Tin exists in different allotropes:
- **Alpha Tin (Grey Tin)**: This is the non-metallic form and is brittle.
- **Beta Tin (White Tin)**: This is the metallic form and is stable at room temperature.

3. **Temperature and Allotropic Transformation**: At lower temperatures (below 13.2 °C), beta tin (white tin) can convert into alpha tin (grey tin). This transformation is a solid-state phase change that affects the crystalline structure of tin.

4. **Effect of Temperature on Tin**: In cold environments, the beta form of tin (white tin) undergoes a transformation into the alpha form (grey tin). This change is driven by the temperature drop, leading to a change in the crystalline structure.

5. **Result of the Transformation**: The alpha tin is brittle and tends to crumble into a grey powder, which is what the soldiers experienced. This phenomenon is commonly referred to as "tin disease" or "tin plague."

6. **Conclusion**: The transformation of the tin buttons from white to grey powder is related to a change in the crystalline structure of tin due to the low temperatures experienced in the Alps.

**Final Answer**: The transformation is related to a change in the crystalline structure of the tin.

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