Question

How many of the following are amphoteric oxides?
$MnO,Mn_{3}O_{4},Mn_{2}O_{3},MnO_{2},Mn_{2}O_{7}$

Answer 1

For oxides of d-block, acidic character increases
with increase in oxidation state of the elements.
Hence, $MnO$ is a basic oxide. $Mn_{3}O_{4}$ , $Mn_{2}O_{3}$ and $MnO_{2}$ are amphoteric oxides while $Mn_{2}O_{7}$ is an acidic oxide.