The atomic number (Z) of an element is 25. In its ground state, how many electrons are present in "N" shell ?

Options

A. 13
B. 2
C. 15
D. 3

Answer

To determine how many electrons are present in the "N" shell of an element with atomic number (Z) 25, we can follow these steps:

### Step 1: Identify the Element
The atomic number (Z) of the element is 25. This corresponds to the element Manganese (Mn).

### Step 2: Write the Electronic Configuration
The electronic configuration of Manganese can be written as:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵

Alternatively, using the noble gas shorthand notation, it can be represented as:
- [Ar] 4s² 3d⁵
Where [Ar] represents the electron configuration of Argon (which accounts for the first 18 electrons).

### Step 3: Count Electrons in Each Shell
Now, we can distribute the electrons into their respective shells:
- K shell (1st shell): 2 electrons (1s²)
- L shell (2nd shell): 8 electrons (2s² 2p⁶)
- M shell (3rd shell): 13 electrons (3s² 3p⁶ 3d⁵)
- N shell (4th shell): 2 electrons (4s²)

### Step 4: Identify the N Shell
The N shell corresponds to the fourth shell (n=4). From our distribution, we see that there are 2 electrons in the N shell.

### Conclusion
Therefore, the number of electrons present in the N shell for the element with atomic number 25 (Manganese) is **2**.

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