Question

Of the following compounds, the most acidic is:

• A. ${As}_2{O}_3$
• B. $P_2{O}_5$
• C. ${Sb}_2{O}_3$
• D. ${Bi}_2{O}_3$

Answer 1

Answer: (B)

$P_2{O}_5$

Generally, acidic nature of oxides increases along a period from left to right and decreases along a group from up to down.
Since $As,P,Sb$ and $Bi$ all belong to $V$ group and arranged in the following manner:
$P:As,Sb,Bi$
$\therefore P_2{O}_5$ is the most and ${Bi}_2{O}_3$ is the least acidic.