`-` Acid:

`+` `HCl`: Hydrochloric acid.

`+` `H_2 SO_4`: Sulfuric acid.

`-` Base: 

`+` `Fe(OH)_2`: Iron `(II)` hydroxide.

`+` `NaOH`: Sodium hydroxide.

`-` Oxide:

`+` `SO_2`: Sulfur dioxide (Oxide acid).

`+` `ZnO`: Zinc oxide (Oxide lưỡng tính).

`+` `SO_3`: Sulfur trioxide (Oxide acid).

`+` `FeO`: Iron `(II)` oxide (Oxide base).

`@`$hoaibao$