Chemistry S & P Block Elements UHS 2024
PMDC Verified Question 2 of 104
Which of the following is not Basic in nature
A
Aluminium oxide
B
Potassium oxide
C
Magnesium oxide
D
Sodium oxide
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Aluminium oxide
Concept:

Metal oxides are generally basic. However, metals near the metalloid "staircase" form oxides that can act as both acids and bases (amphoteric).

Solution:

  • Potassium, Sodium, & Magnesium oxides: These elements are classic s-block metals with low ionization energies. Their oxides dissolve in water to yield \( \text{OH}^- \) ions, making them strictly and strongly basic.
  • Aluminum (Al) is a p-block metal with higher electronegativity and a much smaller, highly charged cation (\( \text{Al}^{3+} \)).
  • Because of this high charge density, Aluminum oxide (\( \text{Al}_2\text{O}_3 \)) is amphoteric.
  • While it can act as a base (reacting with acids), it can also act as an acid (reacting with bases like NaOH to form aluminates).
  • Because it is not exclusively basic and exhibits acidic properties, it is the correct answer.


Why other options are incorrect:

  • Options B, C, and D are classical, strictly basic alkaline/alkali earth oxides.

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