The noble gases have closed-shell electronic cordigaration and are monatomic gases under normal condition .The low bolling points of the ligher noble gases aree due to the weak dispersion points of the ligher noble gases an due to the weak dispersion forces between the atoms and the alsence of other interalumic interactions.
The direct reaction of xenon with flarine loads to a series of compounds with water oxidation number `+2, - 4 and +6, XeF_(4)` reactsviolenatly with water to give `XeO_(2)` .The compound of deduced axbibt nci strouchemistry and their goometries can be deduced considering the total number of electron puirs in the valence shell.
Argon is used in arc welding because of its

Options

A. a.low reactivity with metals
B. b.ability to lower the melting point of metals
C. c.flammability
D. d.high calorific value

Explanation

### Step-by-Step Solution:

1. **Understanding Noble Gases**: Noble gases, such as argon, have a closed-shell electronic configuration, meaning their outermost electron shell is fully filled. This configuration makes them very stable and largely unreactive.

2. **Properties of Noble Gases**: Under normal conditions, noble gases exist as monatomic gases. The lighter noble gases have low boiling points due to weak dispersion forces (also known as London dispersion forces) between their atoms. These forces arise from temporary dipoles that occur when electron distributions around atoms fluctuate.

3. **Reactivity of Xenon**: Xenon is an exception among noble gases as it can react with highly electronegative elements like fluorine. This reaction leads to the formation of various xenon fluorides with different oxidation states, such as +2, +4, and +6. For example, xenon tetrafluoride (XeF4) can react violently with water to produce xenon dioxide (XeO2).

4. **Geometry of Compounds**: The geometry of xenon compounds can be deduced by considering the total number of electron pairs in the valence shell of xenon. This includes both bonding pairs and lone pairs, which helps predict the molecular shape according to VSEPR (Valence Shell Electron Pair Repulsion) theory.

5. **Use of Argon in Arc Welding**: Argon is commonly used in arc welding because it is a noble gas. Its low reactivity means it does not react with the metals being welded, providing an inert atmosphere. This prevents oxidation and contamination of the weld, ensuring a clean and strong bond.

6. **Conclusion**: Therefore, the reason argon is used in arc welding is due to its low reactivity with metals, which allows for effective welding without unwanted chemical reactions.