Boron with hydrogen forms a number of hydrides which are known
are boranes. These hydrides are classified into closoboranes and nidoboranes. The simplest hydride of boron is diborane. Boron
apart from having `(2c, 2e)` bonds also contain `(3c, 2e)` bonds.
Which of the following is an electron-deficient compound ?

Options

A. `B_(2)H_(6)`
B. `B_(4)H_(10)`
C. `CH_(4)`
D. `NH_(3)`

Explanation

To determine which of the given compounds is an electron-deficient compound, we need to analyze the bonding and electron configuration of each compound.

### Step-by-Step Solution:

1. **Understanding Electron Deficiency**:
- An electron-deficient compound is one that does not have a complete octet of electrons around its central atom(s). In simpler terms, it has fewer than 8 electrons in its valence shell.

2. **Identify the Compounds**:
- The compounds given are:
- B2H6 (Diborane)
- B4H10
- CH4 (Methane)
- NH3 (Ammonia)

3. **Analyzing B2H6 (Diborane)**:
- Diborane has a unique structure where it contains 3-center 2-electron (3c-2e) bonds.
- Each boron atom in B2H6 has only 6 electrons around it (3 from the B-H bonds and 2 shared in the B-B bond).
- Therefore, B2H6 is electron-deficient because each boron atom does not achieve a complete octet.

4. **Analyzing B4H10**:
- B4H10 can be considered as a combination of two B2H6 molecules, which also means it retains the electron deficiency characteristic.
- The structure of B4H10 also involves 3c-2e bonds similar to diborane, indicating that it is also electron-deficient.

5. **Analyzing CH4 (Methane)**:
- Methane has a carbon atom bonded to four hydrogen atoms, completing the octet for carbon (4 electrons from carbon and 4 from hydrogen).
- Therefore, CH4 is not electron-deficient.

6. **Analyzing NH3 (Ammonia)**:
- Ammonia has a nitrogen atom bonded to three hydrogen atoms and has a lone pair of electrons.
- Nitrogen has 5 valence electrons, and with 3 shared with hydrogen, it achieves a complete octet.
- Thus, NH3 is not electron-deficient.

7. **Conclusion**:
- The electron-deficient compounds among the given options are **B2H6 and B4H10**.

### Final Answer:
The electron-deficient compounds are **B2H6 and B4H10**.