Question

Which of the following is a neutral oxide?
a) ${{B}_{2}}{{O}_{3}}$
b) $CO$
c) $C{{O}_{2}}$
d) $Si{{O}_{2}}$

Answer 1

Hint: Neutral oxides are those which give a neutral solution on reaction with water, i.e., these compounds neither form acidic nor basic aqueous solutions.Metallic oxides are basic and non-metallic oxides are acidic.

Complete step by step answer:
Let us begin by understanding the concept of acidic, basic and neutral oxides.
Oxides are those binary compounds that are formed as a result of reaction of oxygen. Oxygen is a very reactive element, which combines with both metals and non-metals to form a compound.
Oxides are further classified into acidic, basic and neutral oxides (on the basis of their acidic – basic characteristics).
Acidic oxides are those, which gives an acidic solution on reaction with water. Non-Metals react with oxides to give acidic oxides.
Basic oxides are those, which gives a basic solution on reaction with water. Metals react with oxides to give basic oxides. These are alkali metals, alkali earth metals and lanthanides. They react with dioxygen to give basic oxides and release heat.
Neutral oxides are those, which neither give an acidic nor a basic solution on reaction with water.
Let us take a look at the given options –
1. ${{B}_{2}}{{O}_{3}}$and $Si{{O}_{2}}$- are acidic oxides. Boron is a non-metal. Silicon is a metalloid. The reaction of the respective compounds with water is presented as –
${{B}_{2}}{{O}_{3}}+3{{H}_{2}}O\to 2{{H}_{3}}B{{O}_{3}}$
$Si{{O}_{2}}+2{{H}_{2}}O\to {{H}_{4}}Si{{O}_{4}}$
Both,${{H}_{3}}B{{O}_{3}}$ and ${{H}_{4}}Si{{O}_{4}}$ are acidic in nature.

2. $C{{O}_{2}}$- is an acidic oxide. It dissolves in water to give carbonic acid. The reaction is given as –
$C{{O}_{2}}+{{H}_{2}}O\to {{H}_{2}}C{{O}_{3}}$
Carbonic acid is a strong acid.

3. $CO$ – is a neutral oxide. It is very mildly acidic, but considered neutral as it does not form an acid on reaction with water. The reaction is given as –
$CO+{{H}_{2}}O\to C{{O}_{2}}+{{H}_{2}}$
Carbon dioxide hence produced is mildly acidic in nature, but is not an acid.
Therefore, the answer is – option (b) – CO is a neutral oxide.

Additional Information:
Acidic oxides are generally bonded by covalent bonds, whereas basic oxides are bonded by ionic bonds.

Note: Other than acidic and basic oxides, there are compounds known as amphoteric oxides, which have both acidic and basic characteristics. These oxides react with an acid to give salt and water as a product. This type of reaction is known as neutralization reaction.