Question

How many compounds given below are amphoteric oxides?
$P _{2} O _{5}, P _{2} O _{6}, As _{2} O _{5}, As _{2} O _{6}, Sb _{2} O _{5}, Sb _{4} O _{6}, Bi _{2} O _{3}$

• A. 2
• B. 3
• C. 4
• D. 6

Answer 1

Answer: (A)

The oxides of the type $\overset{+3}{E_{2}} O _{3}$ of $N$ and $P , P _{2} O _{3} ( P _{4} O _{6}$, dimer of $P _{2} O _{3}$) are purely acidic, that of As $( As _{4} O _{6}$, dimer of $As _{2} O _{3})$ and $Sb( Sb _{4} O _{6}$, dimer of $Sb _{2} O _{3})$ amphoteric and that of $Bi (Bi _{2} O _{3})$ is predominantly basic.
The oxides of the type $\overset{+3}{E_{2}} O _{5}$ are more acidic, e.g. $N _{2} O _{5}, P _{2} O _{5}, As _{2} O _{5}, Sb _{2} O _{5}$ So, in the given set of oxides of group- $15$ elements, two oxides are amphoteric, $As _{4} O _{6}$ and $Sb _{4} O _{6}$