Oxides of non-metals can be ______ or ______ in nature.

Non-metals react with Oxygen (O) to form acidic or neutral oxides whereas metals react with Oxygen to form basic or amphoteric oxides.

Acidic oxides: An oxide which exhibits the property of an acid is called as an acidic oxide.

• Acidic oxides react with water to form an acid.
• Example: Sulphur trioxide (SO₃) is an acidic oxide where Sulphur (S) is a non-metal.
• $\underset{(\mathrm{Sulphur}\mathrm{trioxide})}{{\mathrm{SO}}_3\left(\mathrm{l}\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{(\mathrm{Sulphuric}\mathrm{acid})}{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}$

Neutral oxides: The oxides which neither behave as an acid nor as a base on reaction with water are called neutral oxides.

• Neutral oxides are formed by the reaction of non-metals with oxygen.
• Example: Carbon mono-oxide (CO) is a neutral oxide where Carbon (C) is a non-metal.
• $\underset{(\mathrm{Carbon}\mathrm{monooxide})}{\mathrm{CO}}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}}\to \underset{(\mathrm{No}\mathrm{acid}\mathrm{or}\mathrm{base}\mathrm{is}\mathrm{formed})}{\mathrm{No}\mathrm{reaction}}$

Basic oxides: An oxide which exhibits the property of a base is called as a basic oxide.

• Basic oxides react with water to form a base.
• Example: Magnesium Oxide (MgO) is a basic oxide where Magnesium (Mg) is a metal.
• $\underset{(\mathrm{Magnesium}\mathrm{oxide})}{\mathrm{MgO}\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{(\mathrm{Magnesium}\mathrm{hydroxide})}{\mathrm{Mg}{\left(\mathrm{OH}\right)}_2\left(\mathrm{aq}\right)}$

Amphoteric oxides: An amphoteric oxide is an oxide which exhibits the property of an acid as well as a base.

• In general, amphoteric oxides are formed by the reaction of Oxygen with metalloids or elements which resemble closely with metalloids.
• Example: Zinc oxide (ZnO) is an amphoteric oxide where Zinc (Zn) is a metal.
• In the presence of an acid, amphoteric oxides behave as a base to form a salt and water as shown below.
• $\underset{(\mathrm{Zinc}\mathrm{oxide})}{\mathrm{ZnO}\left(\mathrm{s}\right)}+\underset{(\mathrm{Sulphuric}\mathrm{acid})}{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}\to \underset{(\mathrm{Zinc}\mathrm{sulphate})}{{\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$
• In the presence of a base, amphoteric oxides behave as an acid to form a salt and water as shown below.
• $\underset{(\mathrm{Zinc}\mathrm{oxide})}{\mathrm{ZnO}\left(\mathrm{s}\right)}+\underset{(\mathrm{Sodium}\mathrm{hydroxide})}{2\mathrm{NaOH}\left(\mathrm{aq}\right)}\to \underset{(\mathrm{Sodium}\mathrm{zincate})}{{\mathrm{Na}}_2{\mathrm{ZnO}}_2\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

Therefore, oxides of non-metals can be acidic or neutral in nature.