Which of the following is incorrect about interstitial compounds.

Options

A. very reactive
B. high metallic conductivity
C. very hard
D. high melting point.

Answer

To solve the question regarding which statement is incorrect about interstitial compounds, we will analyze each option based on our understanding of interstitial compounds.

### Step-by-Step Solution:

1. **Understanding Interstitial Compounds**:
- An interstitial compound is formed when small atoms (with a small enough radius) occupy the interstitial spaces (holes) in a metal lattice.
- Common examples of small atoms that can form interstitial compounds include hydrogen, carbon, boron, and nitrogen.

2. **Analyzing the Options**:
- **Option 1: Very reactive**:
- Interstitial compounds are generally known to be inert or less reactive. This means they do not readily react with other substances. Therefore, this statement is likely incorrect.

- **Option 2: High metallic conductivity**:
- Interstitial compounds often retain metallic properties, including good electrical conductivity. Thus, this statement is correct.

- **Option 3: Very hard**:
- Many interstitial compounds (like carbides and nitrides) are known for their hardness. This statement is also correct.

- **Option 4: High melting point**:
- Interstitial compounds typically have high melting points due to the strong bonding between the metal and the small atoms. This statement is correct as well.

3. **Conclusion**:
- After analyzing all the options, we find that **Option 1 (Very reactive)** is the incorrect statement about interstitial compounds.

### Final Answer:
The incorrect statement about interstitial compounds is **Option 1: Very reactive**.

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