Noble gases have compleately filled valance shall i.e. `m^(2)sp^(2)` exceps He (i.e) .Noble gases are monoomic under normal conductions .Law bolding point of the ligher noble gases are due to weak van dor wads forces between the atoms and abance of any interature imaractions `Xe` reacts with `F_(2)` so give a sourceof fouoxide mently `XeF_(2),XeF_(4),XeF_(4),XeF_(3)` on complete hydrolyes gives `XeFe_(3)`,
Argon is used in are welding due to its

Options

A. Flammability
B. zero
C. Law reactivityy with metal
D. Lower the melting with metal

Answer

### Step-by-Step Solution:

1. **Understanding Noble Gases**:
- Noble gases, such as helium, neon, argon, krypton, xenon, and radon, have completely filled valence shells. This configuration makes them stable and largely unreactive.
- Exception: Helium has a filled shell configuration of 1s².

2. **Monoatomic Nature**:
- Noble gases exist as monoatomic species under normal conditions, meaning they are found as single atoms rather than molecules.

3. **Low Boiling Points**:
- The lighter noble gases (like helium, neon, and argon) have low boiling points. This is primarily due to weak Van der Waals forces (dispersion forces) between the atoms, which do not require much energy to overcome.

4. **Reactivity of Xenon**:
- Despite being a noble gas, xenon can react with highly electronegative elements such as fluorine. It forms several compounds, including xenon difluoride (XeF₂), xenon tetrafluoride (XeF₄), and xenon trioxide (XeO₃).

5. **Hydrolysis of Xenon Compounds**:
- When xenon fluorides undergo hydrolysis, they can produce xenon oxides, such as xenon trioxide (XeO₃).

6. **Argon in Arc Welding**:
- Argon is commonly used in arc welding due to its inertness. It does not react with metals during the welding process, creating a stable and non-reactive atmosphere that prevents oxidation and contamination.

7. **Conclusion**:
- The primary reason argon is used in arc welding is its low reactivity with metals, which helps maintain an inert atmosphere necessary for effective welding.

### Final Answer:
Argon is used in arc welding due to its low reactivity with metals, which helps create an inert atmosphere that prevents unwanted reactions during the welding process.

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