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)

$P_{2} O_{5}$

Answer 2

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.