Question

Which oxide of manganese is amphoteric ?

• A. $MnO$
• B. $Mn{O}_2$
• C. $M{n}_2{O}_7$
• D. $M{n}_2{O}_3$

Answer 1

The correct option is B $Mn{O}_2$

$Mn{O}_2$ is amphoteric oxide. It has $Mn$ in ${}^{+}4$ oxidation state. It reacts with acid as well as base.
$M{n}_2{O}_7$ is acidic oxide. It has $Mn$ in ${}^{+}7$oxidation state (highest oxidation state). It has covalency with covalently bound $O$ atoms.
$MnO$ is basic oxide. It has $Mn$ in ${}^{+}2$ oxidation state (low oxidation state). It is ionically bound oxide.