The element with atomic number `Z = 118` will be categorised as a:

Options

A. (A) alkali
B. (B) noble gas
C. (C) lanthanide
D. (D) transition element

Explanation

To categorize the element with atomic number \( Z = 118 \), we can follow these steps:

### Step 1: Identify the Element
The element with atomic number 118 is known as Oganesson (Og).

### Step 2: Determine Electronic Configuration
To categorize the element, we need to find its electronic configuration. The electronic configuration can be derived from the atomic number:
- The atomic number 118 means it has 118 electrons.
- The electronic configuration can be written as follows:
\[ [Rn] \, 5f^{14} \, 6d^{10} \, 7s^2 \, 7p^6 \]
Here, \([Rn]\) represents the electron configuration of Radon (atomic number 86).

### Step 3: Identify the Outermost Shell and Valence Electrons
- The outermost shell for Oganesson is the 7th shell.
- The electrons in the outermost shell are:
- \(7s^2\) contributes 2 electrons
- \(7p^6\) contributes 6 electrons
- Therefore, the total number of valence electrons is \(2 + 6 = 8\).

### Step 4: Determine the Group Number
For p-block elements, the group number can be calculated using the formula:
\[ \text{Group Number} = 10 + \text{Number of Valence Electrons} \]
Substituting the number of valence electrons:
\[ \text{Group Number} = 10 + 8 = 18 \]
Elements in group 18 are known as noble gases.

### Step 5: Categorize the Element
Since Oganesson has 8 valence electrons and belongs to group 18, it is categorized as a noble gas.

### Conclusion
Thus, the element with atomic number \( Z = 118 \) is categorized as a **noble gas**.

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