Question

Which of the following can form adducts with lewis base?

• A. $S{O}_2$
• B. $Se{O}_3$
• C. $S{O}_3$
• D. $Se{O}_2$

Answer 1

Answer: (B), (C)

The correct options are
B $Se{O}_3$
C $S{O}_3$

$S{O}_3$ and $Se{O}_3$ are strong lewis acids readily forming crystalline complexes with lewis bases such as pyridine, dioxane and trimethylamine which can be used as sulfonating agents.