Q.53 Chemistry ⭐ 360° Option Elimination Active

NEET 2025 Chemistry Question 53 Solution

Topic: Classification of Elements and Periodicity in Properties · Official NTA Booklet Code 45

Question

Which among the following electronic configurations belong to main group elements? A. [Ne]3s¹ B. [Ar]3d³4s² C. [Kr]4d¹⁰5s²5p⁵ D. [Ar]3d¹⁰4s¹ E. [Rn]5f⁰6d²7s² Choose the correct answer from the option given below:

✓

Verified Against NTA Final Answer Key

Option (2) : A and C only

📚 Classification of Elements and Periodicity in Properties Easy

📋 Given Parameters & Problem Setup

Configuration A [Ne] 3s¹

Configuration B [Ar] 3d³ 4s²

Configuration C [Kr] 4d¹⁰ 5s² 5p⁵

Configuration D [Ar] 3d¹⁰ 4s¹

Configuration E [Rn] 5f⁰ 6d² 7s²

⚡

The 30-Second Exam Hall Shortcut: ⚡ Main Group = s-block or p-block Only

⏱️ Save ~30 seconds

Main group (representative) elements are EXCLUSIVELY s-block and p-block elements! Configuration A is s-block ([Ne]3s¹). Configuration C is p-block (5p⁵). B and D are d-block transition metals; E is actinoid! ⟹ A and C only!

1 Definition: Main Group Elements (also called Representative Elements) are elements whose valence electrons are in s or p orbitals (s-block and p-block).

2 Identify A: [Ne] 3s¹ = Sodium (Group 1, s-block) ⟹ MAIN GROUP.

3 Identify B: [Ar] 3d³ 4s² = Vanadium (Group 5, d-block transition metal) ⟹ NOT main group.

4 Identify C: [Kr] 4d¹⁰ 5s² 5p⁵ = Iodine (Group 17, p-block halogen) ⟹ MAIN GROUP.

5 Identify D: [Ar] 3d¹⁰ 4s¹ = Copper (Group 11, d-block transition metal) ⟹ NOT main group.

6 Identify E: [Rn] 5f⁰ 6d² 7s² = Thorium (Actinoid series) ⟹ NOT main group.

7 Thus, main group elements are A and C only!

8 Select Option (2) in under 10 seconds!

🛡️

Why You Can 100% Trust This Shortcut: IUPAC Periodic Classification of Elements (NCERT Chemistry · Classification of Elements and Periodicity in Properties).

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Canonical Definition of Main Group Elements

In modern chemistry and the NCERT curriculum, "Main Group Elements" (or "Representative Elements") are defined strictly as elements belonging to the s-block (Groups 1 and 2) and the p-block (Groups 13 to 18):

\text{Main Group} = s\text{-block } (ns^{1-2}) \cup p\text{-block } (ns^2 np^{1-6})

• d-block elements are transition elements, and f-block elements are inner transition elements.

Step 2

Classify Configurations A, B, and C

Identify the block and identity of configurations A, B, and C:

A: [\text{Ne}] 3s^1 \implies \text{Na (s-block, Group 1)} \implies \text{Main Group}

• B: [Ar] 3d³ 4s² ⟹ Vanadium (d-block, Group 5, transition metal). Not main group.
• C: [Kr] 4d¹⁰ 5s² 5p⁵ ⟹ Iodine (p-block, Group 17, halogen). Main Group.

Step 3

Classify Configurations D and E

Identify the block and identity of configurations D and E:

D: [\text{Ar}] 3d^{10} 4s^1 \implies \text{Cu (d-block, Group 11)}, \quad E: [\text{Rn}] 5f^0 6d^2 7s^2 \implies \text{Th (Actinoid)}

• Neither D nor E is a main group element.
• Therefore, only configurations A and C belong to main group elements, matching Option (2).

⭐

360° Option Elimination Engine Key Feature

Diagnose every choice: Know exactly why the right option works and why distractors fail.

4-Option Deep Scan

1 A

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. B is a d-block transition metal and E is an actinoid.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing transition and inner transition metals with main group.

2 B

✓ 100% Correct

Verdict & Scientific Reason:

100% correct. A ([Ne]3s¹) is s-block and C ([Kr]4d¹⁰ 5s² 5p⁵) is p-block.

💡

Why this is airtight: None; rigorous periodic classification.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. D is Copper (d-block) and E is Thorium.

⚠️

Student Fallacy (Why candidates pick this trap): Thinking filled d¹⁰ makes Cu a main group element.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Includes Copper (D), which is a transition element.

⚠️

Student Fallacy (Why candidates pick this trap): Falsely considering Group 11 as representative.

⚠️

NTA Trap Alert: Treating Copper ([Ar] 3d¹⁰ 4s¹) as a Main Group Element

Some students see 4s¹ in Copper and think it is an s-block alkali metal! But Copper’s differentiating valence electrons reside in the 3d subshell; it is an official Group 11 transition element!

🛡️ How to avoid the -1 mark: Check the block: s-block (Gr 1-2) & p-block (Gr 13-18) are main group; d and f are not!

📖

Core NEET Syllabus Standard

NEET Chemistry Core Syllabus · Classification of Elements and Periodicity in Properties Standard Benchmark

Core Scientific Principle Tested:

"Representative or Main Group elements comprise s-block and p-block elements."

Syllabus Focus: Electronic Configurations and Types of Elements (s, p, d, f blocks)

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

Main Group = s & p only: A ([Ne]3s¹) and C (5p⁵) ⟹ A & C only!

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NEET 2025 Chemistry Question 53 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Main Group = s-block or p-block Only

Step-by-Step Rigorous Workflow & Mathematical Proof

Canonical Definition of Main Group Elements

Classify Configurations A, B, and C

Classify Configurations D and E

360° Option Elimination Engine Key Feature

NTA Trap Alert: Treating Copper ([Ar] 3d¹⁰ 4s¹) as a Main Group Element

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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