Which one of the following does not exist?

Question

Accepted Answer

Option 2, $NeF_{2}$, is the correct answer because it does not exist. Here's a detailed explanation:

1. **Why Option 2 is Correct:**
   - **Neon (Ne) is a Noble Gas:** Neon is a noble gas with a complete outer electron shell, making it extremely stable and chemically inert. It does not readily form compounds because it has no tendency to gain, lose, or share electrons.
   - **Lack of Reactivity:** Due to its full valence shell, neon does not form bonds with other elements under normal conditions. As a result, $NeF_{2}$ is not a known compound and does not exist.

2. **Why the Other Options are Incorrect:**
   - **Option 1: $XeOF_{4}$**
     - **Existence:** Xenon oxytetrafluoride ($XeOF_{4}$) is a known compound. Xenon, unlike neon, can form compounds because it can expand its valence shell and participate in chemical bonding.
     - **Chemical Properties:** $XeOF_{4}$ is a stable compound formed by xenon, oxygen, and fluorine, demonstrating xenon's ability to form bonds with other elements.
   
   - **Option 3: $XeF_{2}$**
     - **Existence:** Xenon difluoride ($XeF_{2}$) is a well-documented compound. It is one of the simplest xenon compounds and is used as a fluorinating agent.
     - **Chemical Properties:** $XeF_{2}$ is stable and can be synthesized under controlled conditions, showcasing xenon's reactivity with fluorine.

- **Option 4: $XeF_{6}$**
     - **Existence:** Xenon hexafluoride ($XeF_{6}$) is another known compound of xenon. It is one of the three binary fluorides of xenon.
     - **Chemical Properties:** $XeF_{6}$ is a stable compound that can be synthesized and is used in various chemical applications, further illustrating xenon's ability to form compounds with fluorine.

In summary, Option 2, $NeF_{2}$, is the correct answer because neon does not form compounds due to its chemical inertness, while the other options are incorrect as they represent existing compounds of xenon.