Question

What is formed when acidic oxides react with water?
A.Base
B.Acids
C.Salts
D.None of these

Answer 1

Hint:In the above question, we are asked to find out which class of substances are formed when acidic oxides react with water. When acidic oxides react with water, the pH of the solution decreases.

Complete answer:
Oxides can be classified as acidic, basic and amphoteric.
Basic oxides which are also known as basic anhydride. They mainly react with water to form a base and react with acid to form salts.
Amphoteric oxides are the oxides which can act as both acidic and basic oxides.
Acid oxides are the other name of acid anhydride. They are basically oxides of non-metals or metals in high oxidation states. Acidic oxides can be termed as Arrhenius acid but not as Bronsted Lewis acid as they cannot donate protons but then can increase the hydrogen ion concentration of water.
For example,
Carbon dioxide (${\text{C}}{{\text{O}}_{\text{2}}}$) reacts with water (${{\text{H}}_{\text{2}}}{\text{O}}$) to form carbonic acid (${{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$). An enzyme called carbonic anhydrase which is used as a catalyst is named so because of this reaction only
 ${\text{C}}{{\text{O}}_{\text{2}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O }} \to {\text{ }}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$
Similarly, chromium trioxide (${\text{Cr}}{{\text{O}}_3}$) reacts with water to form chromic acid(${{\text{H}}_2}{\text{Cr}}{{\text{O}}_4}$).
${\text{Cr}}{{\text{O}}_3}{\text{ + }}{{\text{H}}_2}{\text{O }} \to {\text{ }}{{\text{H}}_2}{\text{Cr}}{{\text{O}}_4}$
Hence, we can say that acidic oxides react with water to form acids.

So, option C is correct.

Note:
Acidic oxides react with water to form acids.
Acidic oxides react with base to form salts.
Acidic oxides react with basic oxides to form oxoanions.
Acidic oxides are not environmentally friendly. Sulfur and nitrogen oxides are considered air pollutants and react with atmospheric water vapour to produce acid rain.