Which among the following electronic configurations belong to main group elements? A. [Ne]3s^1 B. [Ar]3d^3 4s^2 C. [Kr]4d^10 5s^2 5p^5 D. [Ar]3d^10 4s^1 E. [Rn]5f^0 6d^2 7s^2 Choose the correct answer from the option given below : (1) B and E only (2) A and C only (3) D and E only (4) A, C and D only

The correct answer is Option 2. Full mathematical solution steps and hints are accessible in the interactive StemCET workspace.

Chemistry Q53 – NEET-UG 2025

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Home Chemistry Structure of AtomQuestion #610

Which among the following electronic configurations belong to main group elements? A.

[N e] 3 s^{1}

[A r] 3 d^{3} 4 s^{2}

[K r] 4 d^{10} 5 s^{2} 5 p^{5}

[A r] 3 d^{10} 4 s^{1}

[R n] 5 f^{0} 6 d^{2} 7 s^{2}

Choose the correct answer from the option given below :

Clue 1 of 3: Definition of Main Group Elements

Main group elements are also known as representative elements and are found in the s-block and p-block of the periodic table.

🧠 Full Solution Path

● Video Walkthrough

Step 1: Define Main Group Elements✦ Active

Main group elements are those whose valence electrons occupy only $s$ and $p$ orbitals. These correspond to the $s$ -block (Groups 1 and 2) and $p$ -block (Groups 13-18) of the periodic table. Elements with partially filled $d$ or $f$ orbitals are classified as transition metals or inner transition metals, respectively.

Step 2: Analyze Each Electronic Configuration○ Expand

Let's examine each given electronic configuration:

A. $[N e] 3 s^{1}$ : The valence electron is in the $3 s$ orbital. This is an $s$ -block element (Group 1). Thus, it is a main group element.

B. $[A r] 3 d^{3} 4 s^{2}$ : This configuration has a partially filled $3 d$ orbital. This is a $d$ -block element (transition metal).

C. $[K r] 4 d^{10} 5 s^{2} 5 p^{5}$ : The valence electrons are in the $5 s$ and $5 p$ orbitals. The $4 d^{10}$ subshell is completely filled and acts as a core. This is a $p$ -block element (Group 17). Thus, it is a main group element.

D. $[A r] 3 d^{10} 4 s^{1}$ : This configuration corresponds to Copper (Cu). Although the $3 d$ subshell is full, it is a $d$ -block element (Group 11) and is classified as a transition metal because it can form ions with partially filled $d$ -orbitals (e.g., $C u^{2 +}$ has $3 d^{9}$ ). Therefore, it is not a main group element.

E. $[R n] 5 f^{0} 6 d^{2} 7 s^{2}$ : This configuration has electrons in the $6 d$ orbital. This is a $d$ -block element (transition metal).

💡 Teacher's Secret Hint

Remember that elements with completely filled $d$ -subshells (like Group 11 and 12 elements) are generally still considered $d$ -block elements, with Group 11 being transition metals and Group 12 sometimes referred to as post-transition metals, but not typically main group elements in the strictest sense.

Step 3: Identify the Correct Option○ Expand

Based on the analysis, only configurations A and C belong to main group elements. Therefore, the correct answer is option (2).

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Chemistry Question 53 – NEET-UG 2025

Clue 1 of 3: Definition of Main Group Elements

🧠 Full Solution Path