Consider the following substances :
1. `OF_(2)` 2. `Cl_(2)O` 3. `Br_(2)O`
The correct sequence X - O - X bond angle is

Options

A. `1 gt 2 gt 3`
B. `3gt2gt1`
C. `2 gt 1 gt 3`
D. `1 gt 3 gt2`

Explanation

To determine the correct sequence of the X-O-X bond angles in the substances OF₂, Cl₂O, and Br₂O, we will analyze each molecule step by step.

### Step 1: Draw the Lewis Structures
1. **OF₂ (Oxygen Difluoride)**:
- Oxygen (O) is the central atom with two fluorine (F) atoms attached.
- Oxygen has 2 lone pairs of electrons.
- The structure is:
```
F
\
O
/
F
```
- The bond angle is influenced by the two lone pairs on oxygen which compress the bond angle.

2. **Cl₂O (Dichlorine Monoxide)**:
- Oxygen is the central atom with two chlorine (Cl) atoms attached.
- Oxygen has 2 lone pairs of electrons.
- The structure is:
```
Cl
\
O
/
Cl
```
- Similar to OF₂, the bond angle is influenced by the lone pairs on oxygen.

3. **Br₂O (Dibromine Monoxide)**:
- Oxygen is the central atom with two bromine (Br) atoms attached.
- Oxygen has 2 lone pairs of electrons.
- The structure is:
```
Br
\
O
/
Br
```
- The bond angle is also influenced by the lone pairs on oxygen.

### Step 2: Analyze the Bond Angles
- The bond angles in these molecules are influenced by the size of the halogen atoms (F, Cl, Br) and the presence of lone pairs on oxygen.
- As the size of the halogen increases (F < Cl < Br), the bond angle X-O-X increases due to lesser repulsion from the larger halogen atoms.

### Step 3: Compare the Bond Angles
- **OF₂**: The bond angle is the smallest due to the small size of fluorine and the repulsion from the lone pairs.
- **Cl₂O**: The bond angle is larger than OF₂ because chlorine is larger than fluorine, leading to increased bond angle.
- **Br₂O**: The bond angle is the largest because bromine is the largest halogen, which results in the least repulsion between the bonded atoms.

### Conclusion
The correct sequence of X-O-X bond angles from smallest to largest is:
1. OF₂ (smallest angle)
2. Cl₂O (medium angle)
3. Br₂O (largest angle)

Thus, the final answer is:
**Br₂O > Cl₂O > OF₂** or in numerical terms: **3 > 2 > 1**.

### Final Answer
The correct sequence X-O-X bond angle is: **3, 2, 1**.

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