Which of the following is not a colent seride?

Options

A. BN
B. AIN
C. `Ge_3N_4`
D. `ScN`

Answer

To determine which of the following compounds is not a coolant series, we need to analyze the options provided and identify which one does not belong to the category of coolant series.

### Step-by-Step Solution:

1. **Understanding Coolant Series**:
- Coolant series typically refers to compounds that have a specific structure, often involving nitrogen and other elements, which allow them to act as coolants in various applications.

2. **Identifying the Compounds**:
- The compounds mentioned in the video transcript are:
- Boron nitride (BN)
- Aluminium nitride (AlN)
- Germanium nitride (GeN)
- Thionitrile (SCN)

3. **Analyzing Each Compound**:
- **Boron Nitride (BN)**: This is known to have properties that can be used in high-temperature applications and is part of the coolant series.
- **Aluminium Nitride (AlN)**: This compound is also known for its thermal conductivity and is used in cooling applications, thus part of the coolant series.
- **Germanium Nitride (GeN)**: Similar to the previous compounds, GeN is used in high-temperature applications and is considered a coolant series compound.
- **Thionitrile (SCN)**: This compound does not exhibit the properties associated with coolant series and is not used as a coolant.

4. **Conclusion**:
- Based on the analysis, **Thionitrile (SCN)** is not a coolant series compound. Therefore, the correct answer is option number 4.

### Final Answer:
**Thionitrile (SCN) is not a coolant series compound.**

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