Question

Nature of oxides of non-metal is:
(a) Acidic
(b) Basic
(c) Amphoteric
(d) Neutral

Answer 1

Hint: Let us consider the element S which is non-metal. The two common oxides of sulfur are sulphur dioxide, $\text{S}{{\text{O}}_{2}}$ and sulphur trioxide, $\text{S}{{\text{O}}_{3}}$. These are formed by the reaction of sulphur in presence of catalyst. These oxides further react vigorously with moist air and dissolves in water, liberating heat and sulphuric acid. Thus, the nature of oxides of non-metal can be identified on the basis of this reaction.

Complete step by step solution:
Here, we will get to know both the nature of oxides of metals as well as non-metals along with examples.
Nature of metals with oxygen- Most of the metal react with oxygen and form oxides. The reaction may take place without heating as in sodium, calcium or potassium, while some metals react with oxygen on heating to form oxides.
 \[4\text{Na(s)+}{{\text{O}}_{2}}(\text{g)}\to \text{2N}{{\text{a}}_{2}}\text{O(s)}\]
 \[\text{Mg(s)+}{{\text{O}}_{2}}(\text{g)}\to \text{2MgO(s)}\]
Oxides of metals are basic in nature as they react with water and form bases. We can see this in the example given below. e.g.\[\text{N}{{\text{a}}_{2}}\text{O}\],\[\text{MgO}\] etc.
\[\text{N}{{\text{a}}_{2}}\text{O(s)+}{{\text{H}}_{2}}\text{O(l)}\to \text{2NaOH(aq)}\]
\[\text{CaO(s)+}{{\text{H}}_{2}}\text{O(l)}\to \text{2Ca(OH}{{\text{)}}_{2}}\text{(aq)}\]
Nature of non-metals with oxygen- In general oxides of non-metals are acidic in nature or after dissolving in water they form acids
Carbon dioxide forms carbonic acid with water
\[\text{C}{{\text{O}}_{2}}(\text{g)+}{{\text{H}}_{2}}\text{O(l)}\to {{\text{H}}_{2}}\text{C}{{\text{O}}_{3}}(\text{aq)}\]
Sulphur trioxide forms sulphuric acid with water
\[\text{S}{{\text{O}}_{3}}(g)+{{\text{H}}_{2}}\text{O(l)}\to {{\text{H}}_{2}}\text{S}{{\text{O}}_{4}}(l)\]
Due to their acidic nature, many non-metal oxides directly react with bases to form salts.
Therefore, the correct option is (a) acidic in nature.

Note: We should also know about the amphoteric behaviour of oxides. They react with acids as well as with bases in nature. Such metals are Zinc, Aluminium and Tin etc. The reaction with base as well as acid is shown below-
\[\text{A}{{\text{l}}_{2}}{{\text{O}}_{3}}(s)+6\text{HCl(aq)}\to \text{2AlC}{{\text{l}}_{3}}(aq)+3{{\text{H}}_{2}}\text{O(l)}\]
\[\text{A}{{\text{l}}_{2}}{{\text{O}}_{3}}(s)+2\text{NaOH(aq)}\to \text{2NaAl}{{\text{O}}_{2}}(aq)+{{\text{H}}_{2}}\text{O(l)}\]