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Classification of Elements and Periodicity in Properties appeared 36 times across 3 years — 4.2% of Chemistry. This question is from Periodic Trends.

Year 2026 2025 2024 Total
Questions 9 16 11 36
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Which of the following represents the correct trend for the mentioned property? A. F > P > S > B – First Ionization Energy B. Cl > F > S > P – Electron Affinity C. K > Al > Mg > B – Metallic character D. K₂O > Na₂O > MgO > Al₂O₃ – Basic character Choose the correct answer from the option given below.

Solution & Explanation

Core Logic

Analyzing each statement based on periodic trends:

A. On moving left to right in a period, Ionization Energy (IE) generally increases, and from top to bottom it decreases. So, the correct order is F > P > S > B (IE order). Thus, statement A is correct.

B. For Electron Affinity (EA), Group 17 > Group 16 > Group 15. Also, 3rd-period elements often have higher EA than 2nd period (like Cl > F due to compact size of F). The order Cl > F > S > P is correct. Thus, statement B is correct.

C. On moving left to right in a period, metallic character decreases. So Mg > Al. The correct order is K > Mg > Al > B. Thus, statement C is incorrect.

D. On moving top to bottom in a group basic character increases, and moving left to right it decreases. The correct basic strength order is K₂O > Na₂O > MgO > Al₂O₃. Thus, statement D is correct.

Step 1: Conclusion

Statements A, B, and D represent the correct trends.

Pattern Recognition

Always remember the electron affinity anomaly: Cl > F and S > O due to high inter-electronic repulsion in smaller 2p orbitals.

Chapter Mix

Class 11 Chemistry: Classification of Elements and Periodicity in Properties

Reference Study Guides

Classification Of Elements And Periodicity In Properties

More Classification of Elements and Periodicity in Properties Previous-Year Questions — Page 8

Q70 jee_main_2024_31_jan_morning Electron Gain Enthalpy
The correct sequence of electron gain enthalpy of the elements listed below is A. Ar B. Br C. F D. S Choose the most appropriate from the options given below:
  • A. C > B > D > A
  • B. A > D > B > C
  • C. A > D > C > B
  • D. D > C > B > A

Solution

Core Logic

Electron gain enthalpy (ΔegH) values are considered with their signs when ordering from largest to smallest algebraically.

ElementΔegH (kJ/mol)
F-333
S-200
Br-325
Ar+96

Arranging these algebraically from highest to lowest: +96 > -200 > -325 > -333 Thus, Ar > S > Br > F, which corresponds to A > D > B > C.

Pattern Recognition

Noble gases always have positive electron gain enthalpies (highest algebraically). Halogens have highly negative values (lowest algebraically). Fluorine is highly negative, Bromine is slightly less negative. Sulfur sits in between.

Chapter Mix

Class 11 Chemistry: Classification of Elements and Periodicity in Properties

More Classification of Elements and Periodicity in Properties Questions — jee_main_2026_21_jan_morning

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JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)