The noble gases which do not form any clatherate

Options

A. He
B. Ne
C. As
D. Kr

Explanation

To determine which noble gases do not form any clathrate, we can follow these steps:

### Step 1: Understand Clathrates
Clathrates are compounds formed when gas molecules, such as noble gases, occupy the cavities of a crystal structure, typically made of water (H2O).

**Hint:** Clathrates involve a host structure and guest molecules.

### Step 2: Identify Noble Gases
The noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).

**Hint:** Remember the periodic table and the group of noble gases (Group 18).

### Step 3: Determine Conditions for Clathrate Formation
For a noble gas to form a clathrate, it must be of an appropriate size to fit into the cavities of the crystal structure.

**Hint:** Size is a key factor in the ability to form clathrates.

### Step 4: Evaluate Each Noble Gas
- **Helium (He)**: Too small to fit into the cavities, hence does not form clathrates.
- **Neon (Ne)**: Also too small to fit into the cavities, hence does not form clathrates.
- **Argon (Ar)**: Has an appropriate size and can form clathrates.
- **Krypton (Kr)**: Has an appropriate size and can form clathrates.
- **Xenon (Xe)**: Has an appropriate size and can form clathrates.

**Hint:** Focus on the size of helium and neon compared to argon, krypton, and xenon.

### Step 5: Conclusion
The noble gases that do not form any clathrate are helium and neon.

**Final Answer:** Helium and Neon.