Question

The compound which could not act both as oxidizing as well as reducing agent is

• A. $S{O}_2$
• B. $Mn{O}_2$
• C. $A{l}_2{O}_3$
• D. $CrO$

Answer 1

The correct option is C $A{l}_2{O}_3$

Barrring aluminium, all the other metals here show at least 3 oxidation states, which would make it possible for them to act as both oxidising and reducing agents.
$S:0,+4,+6Mn:0,+2,+4,+6,+7Al:0,+3Cr:0,+3,+6$

Hence, $A{l}_2{O}_3$ cannot act as oxidizing as well as reducing agent.