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p-Block Elements appeared 42 times across 3 years — 4.9% of Chemistry. This question is from Group 13 and 14 Periodic Trends.

Year 2026 2025 2024 Total
Questions 16 13 13 42
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The elements of Group 13 with highest and lowest first ionisation enthalpies are respectively:

Solution & Explanation

Related Formula
Group 13 Ionisation Enthalpy Order: B > Tl > Ga > Al > In
Core Logic

The first ionisation enthalpy trend for Group 13 elements is irregular due to poor shielding by d and f electrons:

  • Boron (B) is the smallest atom in the group with no d-orbital shielding issues, so it has the highest ionisation enthalpy.
  • As we move down, poor shielding by 3d electrons causes a slight increase at Gallium (Ga). Poor shielding by 4f electrons causes a sharp increase at Thallium (Tl).
  • Indium (In) ends up with the weakest effective attraction for its outermost valence electron, giving it the lowest first ionisation enthalpy.

    • Therefore, the highest and lowest elements are B & In respectively.

Pattern Recognition

Group 13 does not follow a linear downward trend. Remember the characteristic 'W' shape or zig-zag pattern of its ionisation energies. Indium sits at the absolute minimum point of this curve.

Chapter Mix

Class 11 Chemistry: The p-Block Elements

More The p-Block Elements Previous-Year Questions — Page 9

Q61 jee_main_2024_31_jan_morning Group 18 Elements
Give below are two statements: Statement-I: Noble gases have very high boiling points. Statement-II: Noble gases are monoatomic gases. They are held together by strong dispersion forces. Because of this they are liquefied at very low temperature. Hence, they have very high boiling points. In the light of the above statements, choose the correct answer from the options given below:
  • A. Statement I is false but Statement II is true.
  • B. Both Statement I and Statement II are true.
  • C. Statement I is true but Statement II is false.
  • D. Both Statement I and Statement II are false.

Solution

Core Logic

Statement I and II are False.

Noble gases have low boiling points. Noble gases are held together by weak dispersion forces.

Pattern Recognition

Noble gases are characterized by extremely weak intermolecular forces (London dispersion forces) because they are monoatomic and non-polar, which directly results in very low boiling and melting points.

Chapter Mix

Class 12 Chemistry: The p-Block Elements

Q79 jee_main_2024_31_jan_morning Group 14 Elements
Consider the oxides of group 14 elements SiO₂, GeO₂, SnO₂, PbO₂, CO and GeO. The amphoteric oxides are
  • A. GeO, GeO₂
  • B. SiO₂, GeO₂
  • C. SnO₂, PbO₂
  • D. SnO₂, CO

Solution

Core Logic

In Group 14 elements, the nature of oxides varies down the group: CO is neutral. CO₂ and SiO₂ are acidic. GeO₂ is distinctly acidic. SnO₂ and PbO₂ are amphoteric.

Pattern Recognition

Tin (Sn) and Lead (Pb) mostly form amphoteric oxides (e.g., SnO, SnO₂, PbO, PbO₂), distinguishing them from the acidic oxides of Carbon and Silicon.

Chapter Mix

Class 11 Chemistry: The p-Block Elements

Rankbit System
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%)