The maximum number of the electrons which are permitted to be assigned to an energy shell of an atom is called the electron capacity of that shell. The distribution of electrons in different orbits or shells is governed by a scheme known as Bohr-Bury scheme. Electrons are filled in the shells in a stepwise manner in increasing order of energy of the energy shell.
What is the maximum electrons capacity of M shell?

Options

A. 24
B. 8
C. 18
D. 32

Explanation

To determine the maximum electron capacity of the M shell, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Shells**: The shells of an atom are designated as K, L, M, N, etc. Each shell corresponds to a principal quantum number (n). The K shell is n=1, L shell is n=2, M shell is n=3, and so on.

2. **Use the Formula for Maximum Electron Capacity**: The maximum number of electrons that can occupy a shell is given by the formula:
\[ \text{Maximum electrons} = 2N^2 \]
where N is the principal quantum number of the shell.

3. **Determine the Value of N for the M Shell**: For the M shell, the principal quantum number (N) is 3.

4. **Substitute N into the Formula**: Now, substitute N = 3 into the formula:
\[ \text{Maximum electrons} = 2 \times (3^2) \]

5. **Calculate**:
\[ 3^2 = 9 \]
Therefore,
\[ \text{Maximum electrons} = 2 \times 9 = 18 \]

6. **Conclusion**: The maximum electron capacity of the M shell is 18 electrons.

### Final Answer:
The maximum electron capacity of the M shell is **18 electrons**.

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