In an atom which has 2K, 8L, 8M and 2N electrons in the ground state, the total number of electrons having l=1 are

Options

A. 20
B. 8
C. 12
D. 10

Explanation

To solve the problem, we need to determine the total number of electrons in an atom that have an azimuthal quantum number \( l = 1 \). The azimuthal quantum number \( l \) corresponds to the type of orbital: \( l = 0 \) for s-orbitals, \( l = 1 \) for p-orbitals, \( l = 2 \) for d-orbitals, and so on.

### Step-by-Step Solution:

1. **Identify the Electron Configuration:**
The atom has the following distribution of electrons:
- K shell: 2 electrons
- L shell: 8 electrons
- M shell: 8 electrons
- N shell: 2 electrons

Therefore, the total number of electrons in the atom is:
\[ 2 + 8 + 8 + 2 = 20 \text{ electrons} \]

2. **Determine the Atomic Number:**
The total number of electrons in a neutral atom is equal to its atomic number. Thus, the atomic number of this atom is 20.

3. **Write the Electron Configuration:**
For an atomic number of 20, the electron configuration can be written as:
\[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2 \]

4. **Identify the Electrons with \( l = 1 \):**
The azimuthal quantum number \( l = 1 \) corresponds to the p-orbitals. We need to count the electrons in the p-orbitals from the electron configuration:
- The 2p orbital has 6 electrons (from \( 2p^6 \)).
- The 3p orbital also has 6 electrons (from \( 3p^6 \)).

Therefore, the total number of electrons with \( l = 1 \) is:
\[ 6 \text{ (from 2p)} + 6 \text{ (from 3p)} = 12 \text{ electrons} \]

5. **Final Answer:**
The total number of electrons having \( l = 1 \) is **12**.