Which of the following is electron deficient ?

Options

A. `(CH_(3))_(2)`
B. `(SiH_(3))_(2)`
C. `(BH_(3))_(2)`
D. `PH_(3)`

Explanation

To determine which of the given compounds is electron deficient, we will analyze each option based on their electron configuration and bonding.

### Step-by-Step Solution:

1. **Identify the Compounds**: The options given are:
- A) CH3 (methyl)
- B) SiH3 (silane)
- C) BH3 (borane)
- D) PH3 (phosphine)

2. **Analyze Each Compound**:
- **A) CH3**:
- Carbon has 4 valence electrons and forms 4 bonds in CH3, which means it has a complete octet. Therefore, CH3 is not electron deficient.

- **B) SiH3**:
- Silicon has 4 valence electrons and forms 4 bonds in SiH3, which also results in a complete octet. Hence, SiH3 is not electron deficient.

- **C) BH3**:
- Boron has 3 valence electrons and forms 3 bonds in BH3. This results in only 6 electrons being involved in bonding (3 bonds x 2 electrons per bond = 6 electrons). Boron does not achieve a complete octet (8 electrons), making BH3 an electron deficient species.

- **D) PH3**:
- Phosphorus has 5 valence electrons and forms 3 bonds in PH3. It has one lone pair of electrons, resulting in a complete octet around phosphorus. Thus, PH3 is not electron deficient.

3. **Conclusion**:
- The only compound that is electron deficient is **C) BH3** (borane).

### Final Answer:
The correct option is **C) BH3**.

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