Which of the following is not properly matched?

Options

A. Particulate matter - Respiratory problems
B. Electrostatic precipitator - Removing particulate matter
C. Catalystic converters - Platinum - Palladium and rhodium
D. Mean annual temperature of earth `-25^@C`

Answer

To solve the question, we need to analyze each of the given pairs and determine which one is not correctly matched.

### Step-by-Step Solution:

1. **Analyze the First Pair: Particulate Matter and Respiratory Problems**
- Particulate matter is known to be released from industries, thermal power plants, and other sources.
- These particles can enter the respiratory system and cause various respiratory problems.
- **Conclusion**: This pair is correctly matched.

2. **Analyze the Second Pair: Electrostatic Precipitators and Removal of Particulate Matter**
- Electrostatic precipitators are devices used to remove particulate matter from industrial emissions.
- They can remove up to 99% of particulate matter by charging the particles and collecting them on plates.
- **Conclusion**: This pair is correctly matched.

3. **Analyze the Third Pair: Catalytic Converters and Reduction of Poisonous Gases**
- Catalytic converters are used in automobiles to reduce harmful emissions.
- They utilize precious metals as catalysts to convert toxic gases into less harmful substances.
- **Conclusion**: This pair is correctly matched.

4. **Analyze the Fourth Pair: Mean Annual Temperature of Earth**
- The mean annual temperature of Earth is approximately 15 degrees Celsius, not in negative values.
- If the option states that the mean annual temperature is in minus, it is incorrect.
- **Conclusion**: This pair is not correctly matched.

### Final Answer:
The pair that is not properly matched is the fourth option regarding the mean annual temperature of Earth.

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