Question

Which of the following oxides is acidic in nature?
A. ${B_2}{O_3}$
B. $A{l_2}{O_3}$
C. $G{a_2}{O_3}$
D. $I{n_2}{O_3}$

Answer 1

Acidic oxides are the oxides that react with water to form an acid, or with a base to form a salt. They are basically the oxides of either nonmetals or metals in high oxidation states.

Complete step by step answer:
Nonmetal oxides react with oxygen to form acidic compounds of oxides which are held together by covalent bonds. These compounds are also known as acid anhydrides. They generally have a low melting and boiling point except for the compounds like ${B_2}{O_3}$ and $Si{O_2}$ which have high melting points and form giant molecules.
Further, depending upon the nature and properties exhibited by compounds, the oxides are classified as:
-Acidic oxides
-Basic oxides
-Amphoteric oxides
-Neutral oxides
Now, among the given oxides ${B_2}{O_3}$ is acidic in nature. When this oxide is treated with water, boric acid is obtained. The reaction is as shown:
${B_2}{O_3} + {H_2}O \to 2{H_3}B{O_3}$
Now taking about the rest of the options, $A{l_2}{O_3}$ and $G{a_2}{O_3}$ are amphoteric in nature i.e. these are the oxides which exhibit both acidic as well as basic characteristics. When these oxides are reacted with acid, they undergo neutralization reaction and form salt and water. Similarly, they react with alkali to form salt and water. The reaction is as shown:
$A{l_2}{O_3} + 6HCl \to 2A{l_3} + 6Cl + 3{H_2}O$
$A{l_2}{O_3} + 2O{H^ - } + 3{H_2}O \to 2{[Al{(OH)_4}]^ - }$
The last option i.e. $I{n_2}{O_3}$ is basic oxide. The reaction is as shown:
$I{n_2}{O_3} + 3{H_2}O \to 2In{(OH)_3}$

Hence, option A is correct.

Note:
There are some compounds that react with oxygen to form oxides but do not exhibit acidic or basic characteristics. Such compounds are known as neutral compounds of oxygen. Some of the examples of such oxides are NO, CO etc.