The tin plague or tin pest or tin disease refers to

Options

A. conversion of stannous to stannic
B. conversion of white tin to grey tin
C. emmision of sound while bending a tin rod
D. atmospheric oxidation of tin

Answer

### Step-by-Step Solution:

1. **Understanding the Terms**:
- The terms "tin plague," "tin pest," and "tin disease" all refer to a specific phenomenon related to tin.

2. **Identifying the Process**:
- The key process involved is the transformation of white tin (also known as beta-tin) into grey tin (also known as alpha-tin).

3. **Characteristics of White and Grey Tin**:
- White tin is the stable form at room temperature and is malleable and ductile.
- Grey tin is the allotropic form that appears when white tin undergoes a phase change, and it is brittle.

4. **Volume Change**:
- The conversion from white tin to grey tin results in an increase in volume, which can lead to the material becoming powdery and disintegrating.

5. **Conclusion**:
- The phenomenon where white tin converts to grey tin, leading to brittleness and powder formation, is known as tin plague, tin pest, or tin disease.

6. **Evaluating Options**:
- Given the options provided:
- **Option 1**: Conversion of stannous to stannic - Incorrect.
- **Option 2**: Conversion of white tin to grey tin - Correct.
- **Option 3**: Emission of sound while bending a tin rod - Incorrect.
- **Option 4**: Atmospheric oxidation of tin - Incorrect.

7. **Final Answer**:
- Therefore, the correct answer is that the tin plague or tin pest refers to the conversion of white tin to grey tin.