Give the decreasing order of the acidic properties of oxides.
a. `ZnO` , b. `KO_(2)` , c. `P_(2)O_(5)` , d. `MgO`

Explanation

a. `Zn^(2+) O^(2-)` , b. `K^(o+)O_(2)^(ɵ)`
c. `overset(+5 xx 2)(P_(2)) overset(-2 xx 5)(O_(5))` , d. `Mg^(2+)O^(2-)`
Since the charge on `MgO` and `ZnO` is same but the size of `Zn^(2+) lt` the size of `Mg^(2+)` (small cation).
OR
`Zn^(2+)` has d-orbitals, so more covalent.
So, decreasing order of acidic character is :
`P_(2)O_(5) gt ZnO gt MgO gt KO_(2) (III gt I gt IV gt II)`