Which of the following statements is not true about noble gases ?

Options

A. Their ionisation energies are very high
B. Their electron affinities are nearly zero
C. They do not from any chemical compounds
D. They are not easily liquefied

Answer

To determine which statement about noble gases is not true, we will analyze each statement one by one.

### Step 1: Analyze Statement 1
**Statement 1:** Their ionization energies are very high.
- Noble gases have a stable electronic configuration (ns² and np⁶), which means they require a significant amount of energy to remove an electron. Therefore, this statement is true.

**Hint:** Remember that ionization energy is related to the stability of the electron configuration.

### Step 2: Analyze Statement 2
**Statement 2:** Their electron affinities are nearly zero.
- Noble gases have a complete outer shell, which means they do not have a tendency to gain electrons. As a result, their electron affinities are indeed very low or nearly zero. This statement is also true.

**Hint:** Consider why elements with full outer shells do not want to gain electrons.

### Step 3: Analyze Statement 3
**Statement 3:** They do not form any chemical compounds.
- While noble gases are generally inert, some of them, such as xenon, krypton, and radon, can form compounds under specific conditions, particularly with highly electronegative elements like fluorine and oxygen. Therefore, this statement is not true.

**Hint:** Think about exceptions in chemistry; some noble gases can react under certain conditions.

### Step 4: Analyze Statement 4
**Statement 4:** They are not easily liquefied.
- Noble gases have weak van der Waals forces between their atoms, which makes them difficult to liquefy. This statement is true.

**Hint:** Recall the nature of intermolecular forces in noble gases.

### Conclusion
After analyzing all the statements, the one that is not true about noble gases is **Statement 3**, which claims that they do not form any chemical compounds.

**Final Answer:** Statement 3 is not true about noble gases.