Choose the correct statement

Options

A. Polar molecules have permanent electric dipole moment
B. `CO_(2)` molecule is a polar molecule
C. `H_(2)O` is a non-polar molecule
D. The dipole field at large distance falls of as `(1)/(r^(2))`

Answer

To solve the question, we need to analyze the statements provided and determine which one is correct based on our understanding of polar and non-polar molecules, as well as the behavior of dipole fields.

### Step-by-Step Solution:

1. **Understanding Polar and Non-Polar Molecules**:
- A polar molecule has a permanent dipole moment due to the uneven distribution of electron density, which results in a positive and a negative end.
- A non-polar molecule has an even distribution of charge, leading to no overall dipole moment.

2. **Analyzing the Statements**:
- **Statement 1**: "Polar molecules have permanent electric dipole moment."
- This statement is true. Polar molecules, by definition, have a permanent dipole moment.

- **Statement 2**: "CO2 is a polar molecule."
- This statement is false. CO2 is a linear molecule with symmetrical charge distribution, resulting in no dipole moment, making it non-polar.

- **Statement 3**: "H2O is non-polar."
- This statement is false. H2O is a bent molecule with an uneven distribution of charge, leading to a permanent dipole moment, thus it is polar.

- **Statement 4**: "Dipole field at large distance falls as r square."
- This statement is false. The electric field due to a dipole falls off as \( \frac{1}{r^3} \) at large distances, not \( \frac{1}{r^2} \).

3. **Conclusion**:
- The only correct statement is **Statement 1**: "Polar molecules have permanent electric dipole moment."

### Final Answer:
The correct statement is: **1. Polar molecules have permanent electric dipole moment.**