The number of electrons in the M-shell of the element with atomic number 24 is :-

Options

A. 24
B. 12
C. 8
D. 13

Answer

To determine the number of electrons in the M-shell of the element with atomic number 24 (chromium), we can follow these steps:

### Step 1: Identify the Element
The element with atomic number 24 is chromium (Cr).

### Step 2: Write the Electronic Configuration
The electronic configuration of chromium (Cr) is:
\[ \text{Cr: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^1 \, 3d^5 \]

### Step 3: Identify the Shells
The shells are designated as follows:
- K-shell: 1s
- L-shell: 2s, 2p
- M-shell: 3s, 3p, 3d
- N-shell: 4s

### Step 4: Count the Electrons in the M-shell
The M-shell includes:
- 3s: 2 electrons
- 3p: 6 electrons
- 3d: 5 electrons

Now, we can sum these:
\[ \text{Total in M-shell} = 2 \, (\text{from } 3s) + 6 \, (\text{from } 3p) + 5 \, (\text{from } 3d) = 2 + 6 + 5 = 13 \]

### Conclusion
The number of electrons in the M-shell of chromium (atomic number 24) is **13**.

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