Which of the following molecule is hypovalent ?

Options

A. `AlF_(3)`
B. `Icl_(2)^(-)`
C. `BCl_(3)`
D. `ICl_(2)^(-)`

Answer

To determine which of the given molecules is hypovalent, we need to understand the concept of hypovalency. Hypovalent molecules are those in which the central atom has fewer than 8 electrons in its valence shell.

### Step-by-Step Solution:

1. **Identify the Central Atoms**:
- The question provides several molecules. We need to identify the central atom in each molecule. The central atoms in the options are Aluminum (Al), Boron (B), and Iodine (I).

2. **Analyze Each Molecule**:
- **Aluminum Fluoride (AlF3)**:
- Aluminum has 3 valence electrons and forms 3 covalent bonds with Fluorine atoms, achieving an octet through bonding. Therefore, it is not hypovalent.
- **Iodine Dichloride (ICl2)**:
- Iodine has 7 valence electrons. In ICl2, it forms 2 bonds with Chlorine and has 3 lone pairs, achieving a complete octet. Thus, it is not hypovalent.
- **Boron Trichloride (BCl3)**:
- Boron has 3 valence electrons and forms 3 covalent bonds with Chlorine atoms. It does not achieve an octet (only has 6 electrons in its valence shell). Therefore, Boron in BCl3 is hypovalent.
- **Aluminum Chloride (AlCl3)**:
- Similar to AlF3, Aluminum forms 3 bonds with Chlorine and can utilize its vacant d-orbitals to expand its octet. Thus, it is not hypovalent.

3. **Conclusion**:
- Among the given options, Boron Trichloride (BCl3) is the only molecule that is hypovalent because Boron has only 6 electrons in its valence shell.

### Final Answer:
The hypovalent molecule is **BCl3**.