Which of the following metal cation oxides is not amphoteric?

How are transition metals and their oxides used in industrial processes?

When $KI$ and $CuSO_4$ solutions are mixed,the products formed are:

$Cr^{2+}$ and $Mn^{3+}$ both possess $d^4$ electronic configuration. Therefore,

Transition metals vary widely in their chemical reactivity. Explain this with examples or write about the reactivity of $3d$ series metals with acids.

Which of the following metal oxides is not amphoteric?