Question

What is the correct sequence of the increasing basic nature of the given oxides?

• A. $\text{K}_{2} \text{O} < \text{N} \text{a}_{2} \text{O} < \text{A} \text{l}_{2} \text{O}_{3} < \text{M} \text{g} \text{O}$
• B. $\text{A} \text{l}_{2} \text{O}_{3} < \text{M} \text{g} \text{O} < \text{N} \text{a}_{2} \text{O} < \text{K}_{2} \text{O}$
• C. $\text{M} \text{g} \text{O} < \text{K}_{2} \text{O} < \text{A} \text{l}_{2} \text{O}_{3} < \text{N} \text{a}_{2} \text{O}$
• D. $\text{M} \text{g} \text{O} < \text{K}_{2} \text{O} < \text{N} \text{a}_{2} \text{O} < \text{A} \text{l}_{2} \text{O}_{3}$

Answer 1

Answer: (B)

Basic nature is directly proportional to the metallic nature.

Metallic nature is inversely proportional to the ionisation enthalpy.

Lesser the ionisation enthalpy, ease of donation of electron and more metallic character due to this most basic oxide will form.

Most metallic oxides are the alkali metal oxides like $\text{K}_{2}\text{O}$ and $\text{Na}_{\text{2}}\text{O}$ are more basic than the $MgO$ because magnesium belongs to the alkaline earth metals and it is less metallic than the alkali metals.

$\text{Al}_{\text{2}}\text{O}_{\text{3}}$ belongs to the amphoteric oxides p-block metal.

Therefore the correct order of the basic strength of the oxides is

$\text{A} \text{l}_{2} \text{O}_{3} < \text{M} \text{g} \text{O} < \text{N} \text{a}_{2} \text{O} < \text{K}_{2} \text{O}$