Chemistry S & P Block Elements UHS 2023
PMDC Verified Question 29 of 104
Which one of them is amphoteric in nature?
A
Lithium oxide
B
Beryllium oxide
C
Calcium oxide
D
Potassium oxide
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Beryllium oxide
Concept:

An amphoteric oxide can act as both an acid and a base, reacting with both to form salt and water. This usually happens at the boundary between metallic and non-metallic elements.

Solution:

  • While most Group 1 and 2 metal oxides are strictly basic, Beryllium (Be) is an exception.
  • Due to its very small atomic size and high charge density (high polarizing power), the Be-O bond has significant covalent character compared to other alkaline earth metals.
  • This unique property allows Beryllium oxide (BeO) to behave amphoterically.
  • It reacts with strong acids (forming \( \text{Be}^{2+} \) salts) and also reacts with strong bases (forming beryllate ions, \( \text{Be(OH)}_4^{2-} \)).


Why other options are incorrect:

  • Lithium, Calcium, & Potassium oxides: These elements have lower charge densities, form highly ionic bonds with oxygen, and are exclusively basic in nature.

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