JEE Main · 2011 · 10 Apr 2011 · Offline · s-Block Elements

Which one of the following order represents the correct sequence of the increasing basic nature of the given oxides ?

(A) $MgO < K_{2} O < Al_{2} O_{3} < Na_{2} O$
(B) $Na_{2} O < K_{2} O < MgO < Al_{2} O_{3}$
(C) $K_{2} O < Na_{2} O < Al_{2} O_{3} < MgO$
(D) $Al_{2} O_{3} < MgO < Na_{2} O < K_{2} O$ ✓ Correct

Answer: (D)

Solution

Basic character of an oxide rises as the metal grows more electropositive, so the amphoteric oxide of aluminium is the least basic, the group-2 oxide of magnesium is more basic, and the group-1 oxides are the most basic of all, with potassium above sodium because basic strength increases down a group. Arranged by increasing basic nature this gives

A l_{2} O_{3} < MgO < N a_{2} O < K_{2} O

JEE Main · 2011 · 10 Apr 2011 · Offline · Single correct option

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JEE Main · 2011 · 10 Apr 2011 · Offline · s-Block Elements

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