The noble gas which form interstitial compound with metals is

Options

A. He
B. Ne
C. Ar
D. Kr or Xe

Answer

To solve the question about which noble gas forms interstitial compounds with metals, we can follow these steps:

### Step 1: Understand Interstitial Compounds
Interstitial compounds are formed when small atoms occupy the spaces (interstices) between the larger atoms in a metal lattice. These compounds typically involve a metal and a smaller non-metal or noble gas.

**Hint:** Think about the size of the atoms involved in forming interstitial compounds.

### Step 2: Identify Noble Gases
The noble gases include Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), and Xenon (Xe). Among these, we need to determine which one is small enough to fit into the interstitial spaces of metals.

**Hint:** Consider the atomic sizes of the noble gases and how they compare to metals.

### Step 3: Compare Sizes
- Helium is the smallest noble gas with an atomic radius of about 31 pm.
- Neon has a larger atomic radius of about 38 pm.
- Argon, Krypton, and Xenon are even larger.

**Hint:** Recall that smaller atoms are more likely to fit into the interstitial spaces of metals.

### Step 4: Conclusion
Since Helium is the smallest noble gas, it can fit into the interstitial spaces of metals, allowing it to form interstitial compounds. Therefore, the correct answer is Helium.

**Final Answer:** The noble gas which forms interstitial compounds with metals is **Helium (He)**.