Most elements form oxides and hydroxides with different characteristics. Often, regular periodic trends are observed in these oxides and hydroxides. Hydroxides of `Na` and `Mg` are distinctly alkaline, while oxides of `N` and `S` are distinctly acidic.
Draw the structure of `B_(2)H_(6)`.
The unusual bond present in `B_(2)H_(6)`is a-
(a)Two centered `3e-` bond `square` , (b)Three centered `2e-` bond `square`
( c)Four centered `2e-` bond `square` , (d)Four centered `4e-` bond `square`
`{:(B_(2)O_(3),"acidic","basic","amphoteric","neutral"),(Al_(2)O_(3),"acidic","basic","amphoteric","neutral"),(Tl_(2)O_(3),"acidic","basic","amphoteric","neutral"):}`

Answer

### Step-by-Step Solution:

**Step 1: Draw the structure of B₂H₆ (Diborane)**
To draw the structure of diborane (B₂H₆), we start with two boron (B) atoms and six hydrogen (H) atoms. The structure can be visualized as follows:

1. Place the two boron atoms in the center.
2. Attach four hydrogen atoms directly to each boron atom (two to each).
3. The remaining two hydrogen atoms will act as bridging hydrogen atoms, connecting the two boron atoms.

The final structure can be represented as:
```
H
|
H--B--H
|
B
/ \
H H
```
In this structure, the two bridging hydrogen atoms are shown connecting the two boron atoms.

**Step 2: Identify the unusual bond in B₂H₆**
In diborane, the bonding involves a unique type of bond known as a "banana bond." This bond is characterized by the sharing of electrons between three centers (the two boron atoms and the bridging hydrogen atoms).

- Each bridging hydrogen atom contributes one electron to the bond, while each boron atom contributes one electron as well.
- Therefore, the unusual bond in B₂H₆ is a three-centered, two-electron bond.

Thus, the correct answer is: **(b) Three centered 2e- bond**.

**Step 3: Determine the nature of the oxides B₂O₃, Al₂O₃, and Tl₂O₃**
Now, we need to classify the oxides based on their acidic, basic, or amphoteric nature:

1. **B₂O₃ (Boron Trioxide)**: This oxide is acidic in nature. It reacts with water to form boric acid (H₃BO₃).

2. **Al₂O₃ (Aluminum Oxide)**: This oxide is amphoteric. It can react with both acids and bases, showing both acidic and basic properties.

3. **Tl₂O₃ (Thallium Oxide)**: This oxide is basic in nature. As we move down the group in the periodic table, the metallic character increases, leading to a more basic oxide.

### Summary of Oxide Nature:
- B₂O₃: Acidic
- Al₂O₃: Amphoteric
- Tl₂O₃: Basic