Which of the following statements are correct ?

Options

A. Solid `Becl_2` is a linear molecule
B. `O_3` molecule is polar in nature
C. Dipole moment of `NH_3` is greater than `NF_3`
D. Resonating structures can have change in arrangement of atoms .

Explanation

To determine which statements are correct, we will analyze each statement one by one based on the information provided.

### Step-by-Step Solution:

1. **Statement 1: Solid BeCl2 is a linear molecule.**
- **Analysis:** In solid form, BeCl2 does not exist as a linear molecule. Instead, it adopts a polymeric structure due to the sp³ hybridization of beryllium. In the solid state, BeCl2 forms a three-dimensional network where beryllium can make four bonds, leading to a non-linear arrangement.
- **Conclusion:** This statement is **false**.

2. **Statement 2: O3 molecule is polar in nature.**
- **Analysis:** Ozone (O3) has a bent structure with a coordinate bond between the oxygen atoms. The presence of this coordinate bond creates a difference in electronegativity between the oxygen atoms, resulting in a dipole moment. Thus, O3 is indeed a polar molecule.
- **Conclusion:** This statement is **true**.

3. **Statement 3: The dipole moment of NH3 is greater than that of NF3.**
- **Analysis:** In NH3, the dipole moments from the hydrogen atoms and the lone pair on nitrogen all point in the same direction, leading to a larger resultant dipole moment. In contrast, in NF3, the dipole moments from the fluorine atoms point downward, while the dipole moment from the lone pair points upward, leading to some cancellation. Therefore, the dipole moment of NH3 is indeed greater than that of NF3.
- **Conclusion:** This statement is **true**.

4. **Statement 4: Resonating structures can have a change in the arrangement of atoms.**
- **Analysis:** Resonating structures must have the same arrangement of atoms; they can only differ in the arrangement of electrons. Therefore, this statement is incorrect.
- **Conclusion:** This statement is **false**.

### Final Conclusion:
The correct statements are **Statement 2** and **Statement 3**.

### Summary of Correct Statements:
- **Correct Statements:** 2 and 3
- **Incorrect Statements:** 1 and 4

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