Classification of Elements and Periodicity in Properties - NEET Previous Year Questions

Chapter Overview

Classification of Elements and Periodicity in Properties is the foundation chapter of Inorganic Chemistry. This chapter consistently contributes 2-3 questions annually in NEET, making it essential for scoring well. The concepts learned here are applied throughout chemistry.

Weightage Analysis

• Average Questions per Year: 2-3
• Success Rate: 75-80%
• Difficulty Level: Easy to Medium
• Most Important Topics: Periodic trends, Ionization energy, Atomic radius

Previous Year Questions Compilation (2009-2024)

2024 Questions

Question 1: NEET 2024

Statement: Which of the following elements has the highest ionization enthalpy?

Options: (A) Na (B) Mg (C) Al (D) Si

Answer: (D) Si

Detailed Solution: Ionization energy generally increases across a period and decreases down a group.

Step-by-step Analysis:

1. All elements are in period 3: Na (Group 1), Mg (Group 2), Al (Group 13), Si (Group 14)
2. Across a period, ionization energy increases due to:
   • Decreasing atomic radius
   • Increasing nuclear charge
   • Increasing effective nuclear charge
3. Order of ionization energy: Na < Mg < Al < Si
4. Exception: Mg > Al due to stable 3s² configuration

Key Concept: Periodic trend of ionization energy with exceptions

Difficulty Level: Easy

Question 2: NEET 2024

Statement: The element with atomic number 35 belongs to:

Options: (A) s-block (B) p-block (C) d-block (D) f-block

Answer: (B) p-block

Detailed Solution:

1. Atomic number 35 = Bromine (Br)
2. Electronic configuration: [Ar] 3d¹⁰ 4s² 4p⁵
3. Valence electrons in p-orbital → p-block element
4. Group 17, Period 4

Key Concept: Block classification based on valence electron configuration

Difficulty Level: Easy

2023 Questions

Question 3: NEET 2023

Statement: Which of the following shows diagonal relationship?

Options: (A) Li and Na (B) Be and Al (C) Mg and Ca (D) B and Si

Answer: (B) Be and Al

Detailed Solution: Diagonal relationship exists between elements positioned diagonally to each other:

1. Be (Group 2, Period 2) and Al (Group 13, Period 3)
2. Similarities due to comparable ionic radii and charge density
3. Common properties: amphoteric oxides, covalent character in compounds

Key Concept: Diagonal relationship and its causes

Difficulty Level: Medium

Question 4: NEET 2023

Statement: The correct order of atomic radii is:

Options: (A) F < Cl < Br < I (B) I < Br < Cl < F (C) Cl < F < Br < I (D) F < Cl < I < Br

Answer: (A) F < Cl < Br < I

Detailed Solution: Atomic radius increases down a group due to:

1. Addition of new electron shells
2. Increased shielding effect
3. Decreased effective nuclear charge
4. Order in Group 17: F < Cl < Br < I

Key Concept: Periodic trend of atomic radius down a group

Difficulty Level: Easy

2022 Questions

Question 5: NEET 2022

Statement: Which of the following has the highest electronegativity?

Options: (A) Na (B) Mg (C) Al (D) Si

Answer: (D) Si

Detailed Solution: Electronegativity increases across a period:

1. All elements in period 3
2. Trend: Na (0.9) < Mg (1.2) < Al (1.5) < Si (1.8)
3. Increases due to increasing effective nuclear charge

Key Concept: Periodic trend of electronegativity

Difficulty Level: Easy

Question 6: NEET 2022

Statement: The element belonging to period 4 and group 14 is:

Options: (A) C (B) Si (C) Ge (D) Sn

Answer: (C) Ge

Detailed Solution:

1. Group 14 elements: C, Si, Ge, Sn, Pb
2. Period 4 contains: Ge (Germanium)
3. Electronic configuration: [Ar] 3d¹⁰ 4s² 4p²

Key Concept: Periodic table positioning

Difficulty Level: Easy

2021 Questions

Question 7: NEET 2021

Statement: Which of the following elements has the largest atomic radius?

Options: (A) Na (B) Mg (C) K (D) Ca

Answer: (C) K

Detailed Solution:

1. Compare periods first: Na, Mg (Period 3) vs K, Ca (Period 4)
2. Period 4 elements are larger than Period 3
3. Within same period: K > Ca (Group 1 > Group 2)
4. Overall order: Na < Mg < Ca < K

Key Concept: Comparison of atomic radii across periods and groups

Difficulty Level: Medium

Question 8: NEET 2021

Statement: The element with electronic configuration [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p² belongs to:

Options: (A) s-block (B) p-block (C) d-block (D) f-block

Answer: (B) p-block

Detailed Solution:

1. Valence electrons: 6s² 6p²
2. Electrons in p-orbital → p-block element
3. This is Lead (Pb), Group 14, Period 6

Key Concept: Block classification based on electronic configuration

Difficulty Level: Easy

2020 Questions

Question 9: NEET 2020

Statement: The correct order of first ionization enthalpy is:

Options: (A) B < C < N < O (B) B < C < O < N (C) C < B < N < O (D) C < B < O < N

Answer: (B) B < C < O < N

Detailed Solution:

1. General trend: Ionization energy increases across period 2
2. Exceptions: B < C (2s²2p¹ < 2s²2p²)
3. O < N due to electron-electron repulsion in 2p⁴ configuration
4. Final order: B < C < O < N

Key Concept: Ionization energy trends with exceptions

Difficulty Level: Medium

Question 10: NEET 2020

Statement: Which of the following is not a lanthanoid?

Options: (A) Ce (B) Pr (C) Lu (D) La

Answer: (D) La

Detailed Solution:

1. Lanthanoids: Ce to Lu (Atomic numbers 58-71)
2. La (atomic number 57) is not a lanthanoid but belongs to Group 3
3. La is the first element of period 6, not part of 4f series

Key Concept: Classification of lanthanoids

Difficulty Level: Easy

2019 Questions

Question 11: NEET 2019

Statement: The element showing maximum deviation from Mendeleev’s original periodic law is:

Options: (A) H (B) He (C) Li (D) Be

Answer: (A) H

Detailed Solution:

1. Hydrogen shows unique properties not fitting any group
2. Can gain one electron (like halogens) or lose one (like alkali metals)
3. Forms H⁺, H⁻, and covalent compounds
4. Doesn’t follow Mendeleev’s law based on atomic mass

Key Concept: Anomalous behavior of hydrogen

Difficulty Level: Medium

Question 12: NEET 2019

Statement: Which of the following has the highest electron affinity?

Options: (A) F (B) Cl (C) Br (D) I

Answer: (B) Cl

Detailed Solution:

1. General trend: Electron affinity becomes less negative down the group
2. Exception: Cl has more negative electron affinity than F
3. Reason: Small size of F causes electron-electron repulsion
4. Order: I < Br < F < Cl

Key Concept: Electron affinity trends with exceptions

Difficulty Level: Medium

2018 Questions

Question 13: NEET 2018

Statement: The atomic radius of elements generally:

Options: (A) Decreases across a period and increases down a group (B) Increases across a period and decreases down a group (C) Decreases both across a period and down a group (D) Increases both across a period and down a group

Answer: (A) Decreases across a period and increases down a group

Detailed Solution:

1. Across period: Decreases due to increasing nuclear charge
2. Down group: Increases due to addition of electron shells
3. These are fundamental periodic trends

Key Concept: Periodic trends of atomic radius

Difficulty Level: Easy

Question 14: NEET 2018

Statement: Which of the following belongs to d-block?

Options: (A) Cu (B) Zn (C) Sc (D) All of these

Answer: (D) All of these

Detailed Solution:

1. d-block includes transition metals (Groups 3-12)
2. Cu (Group 11), Zn (Group 12), Sc (Group 3)
3. All have their d-orbitals incompletely filled (except Zn with d¹⁰)

Key Concept: d-block element classification

Difficulty Level: Easy

2017 Questions

Question 15: NEET 2017

Statement: The element with electronic configuration 2, 8, 18, 8, 2 is:

Options: (A) Ca (B) Sr (C) Ba (D) Ra

Answer: (C) Ba

Detailed Solution:

1. Electronic configuration: 2, 8, 18, 8, 2
2. Total electrons = 2+8+18+8+2 = 38
3. Atomic number 38 = Barium (Ba)
4. Group 2, Period 6 element

Key Concept: Electronic configuration and element identification

Difficulty Level: Easy

Question 16: NEET 2017

Statement: Which of the following properties shows a gradual change across a period?

Options: (A) Atomic radius (B) Ionization enthalpy (C) Electronegativity (D) All of these

Answer: (D) All of these

Detailed Solution: All these properties show gradual variation across a period:

1. Atomic radius: Decreases
2. Ionization enthalpy: Increases
3. Electronegativity: Increases

Key Concept: Periodic properties

Difficulty Level: Easy

2016 Questions

Question 17: NEET 2016 Phase I

Statement: The element which shows similar chemical properties to calcium is:

Options: (A) Na (B) Mg (C) Sr (D) Al

Answer: (C) Sr

Detailed Solution:

1. Similar properties occur in same group
2. Calcium (Ca) is in Group 2
3. Strontium (Sr) is also in Group 2
4. Both are alkaline earth metals

Key Concept: Group properties

Difficulty Level: Easy

Question 18: NEET 2016 Phase II

Statement: The correct order of metallic character is:

Options: (A) Na > Mg > Al > Si (B) Si > Al > Mg > Na (C) Al > Si > Na > Mg (D) Mg > Na > Al > Si

Answer: (A) Na > Mg > Al > Si

Detailed Solution: Metallic character:

1. Decreases across a period
2. Increases down a group
3. Order in period 3: Na > Mg > Al > Si

Key Concept: Metallic character trend

Difficulty Level: Easy

2015 Questions

Question 19: AIPMT 2015

Statement: Which of the following pairs has similar atomic radii?

Options: (A) Na and K (B) Li and Mg (C) Be and Al (D) B and C

Answer: (C) Be and Al

Detailed Solution:

1. Diagonal relationship between Be and Al
2. Similar ionic radii due to diagonal position
3. Charge density and polarizing power similar

Key Concept: Diagonal relationship

Difficulty Level: Medium

Question 20: AIPMT 2015 Cancelled

Statement: The element with highest electronegativity in periodic table is:

Options: (A) F (B) O (C) N (D) Cl

Answer: (A) F

Detailed Solution:

1. Pauling electronegativity values:
   • F: 4.0 (highest)
   • O: 3.5
   • N: 3.0
   • Cl: 3.0
2. Fluorine has highest electronegativity

Key Concept: Electronegativity values

Difficulty Level: Easy

2014 Questions

Question 21: AIPMT 2014

Statement: Which of the following has minimum first ionization enthalpy?

Options: (A) Ca (B) K (C) Sc (D) Rb

Answer: (D) Rb

Detailed Solution:

1. Ionization energy decreases down a group
2. Compare by groups: Rb (Group 1) > K (Group 1) > Ca (Group 2) > Sc (Group 3)
3. Rb is lowest in its group and has lowest IE

Key Concept: Ionization energy comparison

Difficulty Level: Medium

Question 22: AIPMT 2014

Statement: The correct order of electron gain enthalpy is:

Options: (A) O < S < Se < Te (B) Te < Se < S < O (C) O > S > Se > Te (D) Te > Se > S > O

Answer: (A) O < S < Se < Te

Detailed Solution:

1. Electron gain enthalpy becomes less negative down the group
2. Due to increasing atomic size
3. Order: Te < Se < S < O (in terms of magnitude)

Key Concept: Electron gain enthalpy trend

Difficulty Level: Medium

2013 Questions

Question 23: NEET 2013

Statement: Which of the following has highest first ionization energy?

Options: (A) He (B) Ne (C) Ar (D) Kr

Answer: (A) He

Detailed Solution:

1. Ionization energy decreases down a group
2. Noble gases have high ionization energies
3. He has highest due to small size and stable configuration

Key Concept: Noble gas ionization energies

Difficulty Level: Easy

Question 24: NEET 2013

Statement: The element which resembles lithium in its properties is:

Options: (A) Na (B) Be (C) Mg (D) Ca

Answer: (A) Na

Detailed Solution:

1. Elements in same group show similar properties
2. Lithium and Sodium both in Group 1
3. Both are alkali metals with +1 oxidation state

Key Concept: Group properties

Difficulty Level: Easy

2012 Questions

Question 25: AIPMT 2012 Mains

Statement: Which of the following has the lowest ionization energy?

Options: (A) B (B) C (C) N (D) O

Answer: (A) B

Detailed Solution:

1. Generally, ionization energy increases across period 2
2. B has lowest due to electron in 2p orbital
3. Configuration: B (2s²2p¹), C (2s²2p²), N (2s²2p³), O (2s²2p⁴)

Key Concept: Period 2 ionization energies

Difficulty Level: Easy

Question 26: AIPMT 2012 Prelims

Statement: The element belonging to group 13 and period 3 is:

Options: (A) B (B) Al (C) Ga (D) In

Answer: (B) Al

Detailed Solution:

1. Group 13 elements: B, Al, Ga, In, Tl
2. Period 3 contains Al
3. Aluminum has configuration [Ne] 3s²3p¹

Key Concept: Periodic table positioning

Difficulty Level: Easy

2011 Questions

Question 27: AIPMT 2011 Mains

Statement: Which of the following pairs is isoelectronic?

Options: (A) Na⁺ and Mg²⁺ (B) O²⁻ and F⁻ (C) N³⁻ and O²⁻ (D) All of these

Answer: (D) All of these

Detailed Solution:

1. Na⁺ (10e⁻), Mg²⁺ (10e⁻) - both have 10 electrons
2. O²⁻ (10e⁻), F⁻ (10e⁻) - both have 10 electrons
3. N³⁻ (10e⁻), O²⁻ (10e⁻) - both have 10 electrons
4. All pairs are isoelectronic

Key Concept: Isoelectronic species

Difficulty Level: Easy

Question 28: AIPMT 2011 Prelims

Statement: The element with atomic number 56 belongs to:

Options: (A) s-block (B) p-block (C) d-block (D) f-block

Answer: (A) s-block

Detailed Solution:

1. Atomic number 56 = Barium (Ba)
2. Electronic configuration: [Xe] 6s²
3. Valence electrons in s-orbital → s-block
4. Group 2, Period 6

Key Concept: Block classification

Difficulty Level: Easy

2010 Questions

Question 29: AIPMT 2010 Mains

Statement: Which of the following shows maximum oxidation state?

Options: (A) Mn (B) Fe (C) Cr (D) Co

Answer: (A) Mn

Detailed Solution:

1. Maximum oxidation states:
   • Mn: +7 (in KMnO₄)
   • Fe: +6 (in FeO₄²⁻)
   • Cr: +6 (in K₂Cr₂O₇)
   • Co: +5 (rare)
2. Manganese shows highest oxidation state

Key Concept: Oxidation states of transition metals

Difficulty Level: Medium

Question 30: AIPMT 2010 Prelims

Statement: The correct order of atomic radius is:

Options: (A) Na⁺ > Mg²⁺ > Al³⁺ > F⁻ (B) Na⁺ < Mg²⁺ < Al³⁺ < F⁻ (C) Al³⁺ < Mg²⁺ < Na⁺ < F⁻ (D) F⁻ < Na⁺ < Mg²⁺ < Al³⁺

Answer: (C) Al³⁺ < Mg²⁺ < Na⁺ < F⁻

Detailed Solution:

1. For isoelectronic species (10e⁻): Al³⁺ < Mg²⁺ < Na⁺
2. F⁻ has 10 electrons but larger size
3. Order: Al³⁺ < Mg²⁺ < Na⁺ < F⁻

Key Concept: Ionic radii of isoelectronic species

Difficulty Level: Medium

2009 Questions

Question 31: AIPMT 2009

Statement: Which of the following has the highest electronegativity?

Options: (A) B (B) C (C) N (D) O

Answer: (D) O

Detailed Solution:

1. Electronegativity increases across period 2
2. Pauling values: B (2.0), C (2.5), N (3.0), O (3.5)
3. Oxygen has highest electronegativity

Key Concept: Periodic trend of electronegativity

Difficulty Level: Easy

Question 32: AIPMT 2009

Statement: The element belonging to period 3 and group 17 is:

Options: (A) F (B) Cl (C) Br (D) I

Answer: (B) Cl

Detailed Solution:

1. Group 17 (Halogens): F, Cl, Br, I
2. Period 3 contains Cl
3. Chlorine configuration: [Ne] 3s²3p⁵

Key Concept: Periodic table positioning

Difficulty Level: Easy

Topic-wise Analysis

1. Periodic Trends (40% of questions)

Key Concepts:

• Atomic radius trends
• Ionization energy variations
• Electronegativity patterns
• Electron affinity trends

Common Mistakes:

• Not considering exceptions to trends
• Confusing order of elements
• Forgetting diagonal relationships

2. Electronic Configuration (25% of questions)

Key Concepts:

• Writing electronic configurations
• Identifying blocks
• Valence electron determination
• Period and group identification

Common Mistakes:

• Incorrect order of orbital filling
• Misidentifying blocks
• Confusing periods and groups

3. Classification Methods (20% of questions)

Key Concepts:

• Mendeleev’s periodic law
• Modern periodic law
• Block classification
• Group properties

Common Mistakes:

• Confusing old and modern classification
• Misunderstanding block classification
• Not knowing group properties

4. Special Cases (15% of questions)

Key Concepts:

• Diagonal relationships
• Anomalous behavior
• Exceptional cases
• Isoelectronic species

Common Mistakes:

• Not memorizing exceptions
• Missing diagonal relationships
• Confusing isoelectronic series

Year-wise Distribution

Concept Weightage Analysis

High Weightage Topics (30+ questions over 16 years):

1. Periodic Trends - Atomic radius, IE, EN
2. Electronic Configuration - Block classification
3. Element Identification - Period and group

Medium Weightage Topics (15-30 questions):

1. Classification Methods - Old vs Modern
2. Comparative Properties - Size, reactivity
3. Exception Cases - Anomalies

Low Weightage Topics (<15 questions):

1. Historical Development - Mendeleev’s contributions
2. Advanced Concepts - Crystal field theory basics

Success Rate by Topic

Preparation Strategy

Phase 1: Concept Building (1 week)

1. Master periodic trends

   • Atomic radius (size, factors affecting)
   • Ionization energy (trends, exceptions)
   • Electronegativity (Pauling scale)
   • Electron affinity (trends)

2. Learn electronic configurations

   • Orbital filling order
   • Block classification rules
   • Valence electron identification

3. Understand classification

   • Mendeleev vs Modern periodic table
   • Block classification (s, p, d, f)
   • Group properties

Phase 2: PYQ Practice (1 week)

1. Solve by difficulty level

   • Start with easy questions
   • Progress to medium difficulty
   • Focus on special cases

2. Identify patterns

   • Common question types
   • Frequently tested concepts
   • Year-wise preferences

3. Learn from mistakes

   • Analyze incorrect answers
   • Understand conceptual gaps
   • Review related topics

Phase 3: Revision (3-4 days)

1. Quick revision notes

   • Periodic trends table
   • Exception cases
   • Important element positions

2. Practice tests

   • Time-bound practice
   • Simulate exam conditions
   • Improve speed and accuracy

Quick Reference Tables

Periodic Trends Summary

Block Classification Rules

Important Exception Cases

1. Diagonal Relationships

   • Li ↔ Mg
   • Be ↔ Al
   • B ↔ Si

2. Ionization Energy Exceptions

   • Be > B (stable 2s²)
   • N > O (stable 2p³)
   • Mg > Al (stable 3s²)

3. Size Anomalies

   • F < Cl (small size effect)
   • Al³⁺ < Mg²⁺ < Na⁺ (isoelectronic)

Practice Questions

Additional Practice (Not in PYQs)

1. Question: Which element has configuration [Ar] 3d¹⁰ 4s² 4p³? Answer: As (Arsenic), Group 15, Period 4

2. Question: Arrange in increasing order of IE: Na, K, Mg, Ca Answer: K < Na < Ca < Mg

3. Question: Element with maximum metallic character: Na, Mg, Al, Si Answer: Na

4. Question: Which pair shows diagonal relationship? Answer: Be and Al

Video Resources

Chapter Videos

1. Introduction to Periodic Classification - 45 min
2. Periodic Trends - Part 1 - 50 min
3. Periodic Trends - Part 2 - 45 min
4. Electronic Configuration and Blocks - 40 min
5. Special Cases and Exceptions - 35 min
6. PYQ Solutions (2009-2024) - 90 min

📺 Access Complete Video Playlist

Final Tips for Exam

During Exam

1. Read questions carefully - Look for key terms
2. Eliminate wrong options - Use process of elimination
3. Apply trends systematically - Don’t skip steps
4. Watch for exceptions - Check if special case applies
5. Manage time - Spend 45-60 seconds per question

Common Pitfalls to Avoid

1. Don’t assume trends - Always verify with position
2. Don’t ignore exceptions - They’re frequently tested
3. Don’t confuse periods and groups - Double-check
4. Don’t rush electronic configurations - Follow order
5. Don’t memorize without understanding - Know the reasons

Summary

• Total Questions to Study: 32+ questions from 2009-2024
• Focus Areas: Periodic trends, electronic configuration, element identification
• Success Strategy: Master concepts, practice PYQs, learn exceptions
• Time Allocation: 45-60 seconds per question in exam
• Target Score: Aim for 100% accuracy in this chapter

This comprehensive coverage of Classification of Elements and Periodicity will help you score maximum marks in this foundational chapter of Inorganic Chemistry.

Compiled by SATHEE Team, IIT Kanpur | Last Updated: October 2024