The number of three centre two electron bonds in a molecule of diborane is________.

Options

A. `0`
B. `2`
C. `4`
D. `6`

Answer

To determine the number of three-center two-electron bonds in a molecule of diborane (B₂H₆), we can follow these steps:

### Step 1: Understand the Structure of Diborane
Diborane consists of two boron atoms and six hydrogen atoms. The boron atoms are at the center, and the hydrogen atoms are arranged around them.

**Hint:** Recall that diborane has a unique structure that involves bridging hydrogen atoms.

### Step 2: Draw the Lewis Structure
To visualize the bonding in diborane, we can draw its Lewis structure. In diborane, each boron atom forms four bonds, but due to the presence of bridging hydrogen atoms, the structure is not a simple tetrahedral arrangement.

**Hint:** Look for the bridging hydrogen atoms that connect the two boron atoms.

### Step 3: Identify Three-Center Two-Electron Bonds
In diborane, the bonding involves two types of hydrogen atoms:
1. Terminal hydrogen atoms, which are bonded to one boron atom.
2. Bridging hydrogen atoms, which are bonded to both boron atoms.

The bridging hydrogen atoms create three-center two-electron bonds. Each of these bonds involves three atoms (two boron and one hydrogen) sharing two electrons.

**Hint:** Count how many bridging hydrogen atoms are present in the structure.

### Step 4: Count the Three-Center Two-Electron Bonds
In the diborane molecule, there are two bridging hydrogen atoms. Each bridging hydrogen forms a three-center two-electron bond involving the two boron atoms and the hydrogen atom.

**Hint:** Remember that each bridging hydrogen contributes to one three-center two-electron bond.

### Step 5: Conclusion
Thus, in a molecule of diborane, there are a total of **two three-center two-electron bonds**.

**Final Answer:** The number of three-center two-electron bonds in a molecule of diborane is **2**.

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