Question

Match List-I with List-II

Choose the correct answer from the options given below:

• (A) - (I), (B) - (II), (C) - (III), (D) - (IV)
• (A) - (I), (B) - (III), (C) - (IV), (D) - (II)
• (A) - (IV), (B) - (III), (C) - (I), (D) - (II)
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)

Hint:

To solve electron configuration questions quickly, remember the atomic numbers of the first 20 elements.
Li (3) $\rightarrow$ 2, 1
Na (11) $\rightarrow$ 2, 8, 1
Mg (12) $\rightarrow$ 2, 8, 2
Cl (17) $\rightarrow$ 2, 8, 7

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The electronic configuration of an atom describes the distribution of its electrons in different energy levels or shells (K, L, M, N...) surrounding the nucleus.
According to Bohr's atomic model, the maximum number of electrons that can be accommodated in any shell is given by the formula \( 2n^2 \), where \( n \) is the principal quantum number (shell number).
Thus, the first shell (K) can hold up to 2 electrons, the second shell (L) up to 8, and the third shell (M) up to 18 (though stable with 8 as an octet).
To find the electronic configuration, we must know the atomic number (\( Z \)) of the elements, which represents the total number of protons (and also electrons in a neutral atom).

Step 2: Detailed Explanation:
Let us determine the electronic configurations of the listed elements individually:
(A). Magnesium (Mg):
The atomic number of Magnesium is \( Z = 12 \).
Distributing these 12 electrons in shells:
K-shell: 2 electrons
L-shell: 8 electrons
M-shell: 2 electrons
Therefore, the configuration is 2, 8, 2, which matches with (IV).
(B). Sodium (Na):
The atomic number of Sodium is \( Z = 11 \).
Distributing these 11 electrons:
K-shell: 2 electrons
L-shell: 8 electrons
M-shell: 1 electron
Therefore, the configuration is 2, 8, 1, which matches with (III).
(C). Lithium (Li):
The atomic number of Lithium is \( Z = 3 \).
Distributing these 3 electrons:
K-shell: 2 electrons
L-shell: 1 electron
Therefore, the configuration is 2, 1, which matches with (I).
(D). Chlorine (Cl):
The atomic number of Chlorine is \( Z = 17 \).
Distributing these 17 electrons:
K-shell: 2 electrons
L-shell: 8 electrons
M-shell: 7 electrons
Therefore, the configuration is 2, 8, 7, which matches with (II).
Combining these pairings: (A) - (IV), (B) - (III), (C) - (I), (D) - (II).
This matches option (C).

Step 3: Final Answer:
Therefore, the correct match is represented by option (C).