The chemistry of zero group elements is little known because 

Options

A. They are less abundant
B. They have low ionisation potential
C. They have octet configuration
D. They have low boiling points

Answer

### Step-by-Step Solution:

1. **Understanding Zero Group Elements**:
- Zero group elements refer to the noble gases, which are located in Group 18 of the periodic table. These include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).

2. **Electron Configuration**:
- Noble gases have a complete outer shell of electrons. Helium has a configuration of 1s², while the other noble gases have an electron configuration of ns²np⁶. This complete octet (or full outer shell) contributes to their stability.

3. **Reactivity**:
- Due to their complete octet configuration, noble gases are very stable and exhibit very low reactivity. This means they do not readily form compounds with other elements, which is a key reason why their chemistry is not well understood.

4. **Ionization Potential**:
- Noble gases have high ionization potentials because removing an electron from a complete octet would disturb their stable configuration. This high ionization potential further contributes to their low reactivity.

5. **Abundance**:
- While noble gases are present in the atmosphere (about 1% of the total volume of air), their low reactivity means they do not participate in chemical reactions that would make their chemistry more well-known.

6. **Boiling Points**:
- Noble gases have low boiling points, but this characteristic alone does not explain why their chemistry is less known. Other gases with low boiling points can be highly reactive and thus have well-known chemistry.

7. **Conclusion**:
- The primary reason the chemistry of noble gases is little known is due to their complete octet configuration, which leads to their low reactivity.

### Final Answer:
The chemistry of zero group elements (noble gases) is little known primarily because they have a complete octet configuration, resulting in very low reactivity.

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