Which one of the following statement is not correct?

Options

A. a.Ar is used in electric bulb
B. b.Kr is obtained during redioactive decay
C. c.Boiling point of helium to the lowest among all noble gases
D. d.`Xe` forms `XeOF_(4)`

Answer

To determine which statement about noble gases is incorrect, we will analyze each of the provided statements one by one.

### Step-by-Step Solution:

1. **Identify the Noble Gases**:
- The noble gases, also known as inert gases, belong to Group 18 of the periodic table. They include Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).

2. **Evaluate Statement A**:
- **Statement**: Argon is used in electric bulbs.
- **Analysis**: This statement is true. Argon is indeed used in electric bulbs because of its inert nature, which prevents the filament from oxidizing and prolongs the life of the bulb.

3. **Evaluate Statement B**:
- **Statement**: Krypton is obtained during radioactive decay.
- **Analysis**: This statement is incorrect. Krypton is not produced during radioactive decay; rather, it is found in the Earth's atmosphere and in various minerals. Radon, another noble gas, is the one that is produced during radioactive decay.

4. **Evaluate Statement C**:
- **Statement**: The boiling point of helium is the lowest among noble gases.
- **Analysis**: This statement is true. Helium has the lowest boiling point of all the noble gases due to its low molecular weight and weak Van der Waals forces.

5. **Evaluate Statement D**:
- **Statement**: Xenon forms XeOF4.
- **Analysis**: This statement is true. Xenon can form various compounds, including XeOF4, with highly electronegative elements such as fluorine and oxygen.

6. **Conclusion**:
- After evaluating all the statements, we find that the incorrect statement is **Statement B**: "Krypton is obtained during radioactive decay."

### Final Answer:
The incorrect statement is **B: Krypton is obtained during radioactive decay**.