Question

Which of the following oxide is amphoteric in nature?
A.$N{a_2}O$
B.$L{i_2}O$
C.${K_2}O$
D.$A{l_2}{O_3}$

Answer 1

Let’s first see what amphoteric means: an amphoteric compound is a molecule or ion that can react both as an acid and as a base. What exactly this can mean depends on which definitions of acids and bases are being used. One type of amphoteric species are amphiprotic molecules, which can either donate or accept a proton. This is what amphoteric means in Bronsted Lowry acid-base theory.

Complete answer:
Amphoteric substances are substances that display both acidic and basic properties, so they can act as either acids or bases. If an amphoteric substance reacts with a base, then it will take on the role of an acid by being an electron acceptor or proton donor.
Aluminium oxide is an amphoteric oxide because it reacts with acids as well as bases and gives salts and water. Reaction with acid When Aluminium oxide reacts with Hydrochloric acid it gives Aluminium chloride and water. Aluminium oxide contains oxide ions so react with dilute hydrochloric acid.
It has reactions as both a base and an acid. The oxide ions are held too strongly in the solid lattice to react with the water. Reaction with acids: Aluminum oxide contains oxide ions, and thus reacts with acids in the same way sodium or magnesium oxides do.
So, the correct answer is (D) $A{l_2}{O_3}$.

Note:
Ampholytes are amphoteric molecules that contain both acidic and basic groups and will exist mostly as zwitterions in a certain range of $pH$. The $pH$ at which the average charge is zero is known as the molecule's isoelectric point. Ampholytes are used to establish a stable $pH$ gradient for use in isoelectric focusing.