If compound `AX_(3)` is a hypervalent compound then the group no of element A is :-

Options

A. III A
B. V A
C. VI A
D. VII A

Answer

To determine the group number of element A in the hypervalent compound AX₃, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Hypervalency**:
- A hypervalent compound is one where the central atom can hold more than eight electrons in its valence shell. This typically occurs in elements from the third period and below in the periodic table.

2. **Analyze the Compound AX₃**:
- In the formula AX₃, A is the central atom and X represents three surrounding atoms. Given that X is a halogen, it typically belongs to Group 17 (or VIIA) of the periodic table.

3. **Determine the Group of A**:
- Since A is hypervalent, it must be able to expand its octet. Elements that can do this are usually found in Group 15 (VA), Group 16 (VIA), or Group 17 (VIIA). However, for A to form a compound with three halogen atoms, it is most likely to be from Group 15.

4. **Identify Common Elements**:
- Common elements in Group 15 that can form AX₃ type compounds include phosphorus (P) and arsenic (As). These elements can accommodate more than eight electrons due to the availability of d-orbitals.

5. **Conclusion**:
- Therefore, the group number of element A in the hypervalent compound AX₃ is Group 15.

### Final Answer:
The group number of element A is **15**.