Which inert gas has abnormal behaviour on liquefaction ?

Options

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

Answer

To solve the question "Which inert gas has abnormal behaviour on liquefaction?", we can follow these steps:

### Step 1: Understand the Question
The question asks us to identify which inert gas exhibits abnormal behavior when it is liquefied. Inert gases, also known as noble gases, include helium, neon, argon, krypton, and xenon.

**Hint:** Focus on the properties of the inert gases and their behavior during liquefaction.

### Step 2: Analyze the Options
The options given are:
- A) Xenon
- B) Helium
- C) Argon
- D) Krypton

**Hint:** Consider the characteristics of each gas, especially their size and intermolecular forces.

### Step 3: Consider the Properties of Inert Gases
- **Helium**: It has a very small atomic size and exhibits nearly ideal gas behavior. This means it does not condense easily and has unique properties when liquefied.
- **Xenon**: It is larger and has stronger van der Waals forces compared to helium.
- **Argon and Krypton**: These gases also have larger atomic sizes than helium and do not show the same abnormal behavior as helium.

**Hint:** Think about why smaller gases might behave differently than larger ones during liquefaction.

### Step 4: Identify the Abnormal Behavior
Helium is known to have abnormal behavior during liquefaction due to its small size and the fact that it remains a liquid at very low temperatures. It does not behave like other gases when liquefied, which is why it is considered to have abnormal behavior.

**Hint:** Recall that abnormal behavior in this context refers to deviations from expected gas behavior under liquefaction conditions.

### Step 5: Conclusion
Based on the analysis, we conclude that the inert gas that exhibits abnormal behavior on liquefaction is **B) Helium**.

**Final Answer:** B) Helium