Question

A non-metallic oxide dissolves in water to give:
A.Alkali
B.Acid
C.Base
D.None of these

Answer 1

The acidic or basic solutions formed by the dissolution of various oxides is classified according to the Arrhenius theory of acids and bases. If hydrogen ions are released then the solution is said to be acidic and if hydroxide ions are released then the solution is said to be basic.

Complete answer:
The nature of a solution containing any compound in water is decided by the nature of the compound itself.
Non-metallic elements are the elements that occupy the extreme right positions in the modern periodic table. These elements are identified by their characteristic properties like high electron gain enthalpies, high ionization enthalpies, smaller atomic radii and high electronegativity values.
The oxides formed between non-metallic elements involve those elements that are usually less electronegative than oxygen (the fluoride of oxygen or oxides of fluorine are exceptions). These oxides are mainly covalent in nature.
Metallic oxides have a tendency to form alkalis on dissolving in water and are mainly basic in nature. Non-metallic oxides like carbon dioxide, sulphur oxides and nitrogen oxides are acidic in nature. Thus, their solution in water gives an acidic solution.
Examples include:
Carbon dioxide dissolves in water to give a weak mineral acid known as carbonic acid. The reaction can be shown as follows:
$C{O_2} + {H_2}O \to {H_2}C{O_3}$
Nitrogen dioxide on dissolution in water gives nitric acid. The reaction can be shown as follows:
$3N{O_2} + {H_2}O \to 2HN{O_3} + NO$

Note:
The distinction between an acidic or basic solution can be made determining the pH of the solution. Another method of identifying the type of solution is through acid-base indicators like methyl orange, litmus paper and phenolphthalein.