`BaO_(2)` is a peroxide, but `PbO_(2)` is not a peroxide. Why?

Explanation

Metallic oxides which on treatment with dilute acids produce hydrogen peroxide are called peroxides.All peroxides contain a peroxide ion `(O_(2)^(2-))` having the structure `[O-O]^(2).PbO_(2)` does not contain peroxide ion and hence it cannot be called a peroxide.