The atomic numbers of the elements X, Y and Z are 2, 10 and 16, respectively. Identify the element which does not exist in monoatomic state.

Options

A. X
B. Z
C. Y
D. X and Y

Explanation

To determine which element among X, Y, and Z does not exist in a monoatomic state, we can follow these steps:

### Step 1: Identify the Elements
- The atomic numbers given are:
- Element X: Atomic number 2
- Element Y: Atomic number 10
- Element Z: Atomic number 16

### Step 2: Determine the Elements
- Using the periodic table:
- Element X (Atomic number 2) is Helium (He).
- Element Y (Atomic number 10) is Neon (Ne).
- Element Z (Atomic number 16) is Sulfur (S).

### Step 3: Analyze the Electronic Configurations
- Next, we need to find the electronic configurations of these elements:
- Helium (He): 1s² (2 electrons)
- Neon (Ne): 1s² 2s² 2p⁶ (10 electrons)
- Sulfur (S): 1s² 2s² 2p⁶ 3s² 3p⁴ (16 electrons)

### Step 4: Determine Stability
- Elements with a complete outer shell (stable configuration) tend to exist in a monoatomic state:
- Helium has a complete outer shell (2 electrons in the K shell).
- Neon has a complete outer shell (8 electrons in the L shell).
- Sulfur has 6 electrons in its valence shell (3rd shell) and needs 2 more electrons to achieve stability.

### Step 5: Conclusion
- Since Helium and Neon have stable electronic configurations, they can exist in a monoatomic state.
- Sulfur, on the other hand, is reactive because it seeks to gain 2 more electrons to achieve a stable configuration. Therefore, it does not exist in a monoatomic state.

### Final Answer
The element that does not exist in a monoatomic state is **Sulfur (Element Z, Atomic number 16)**.

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