Question

An amphoteric substance is :

• A. a substance that can act as both acids and base by being both proton acceptor and proton donor
• B. a substance that acts as an acid by being both a proton acceptor and a proton donor
• C. a substance that acts as a base by being both a proton acceptor and a proton donor
• D. when a hydronium ion from a base reacts with a hydroxide ion from an acid to make water and a salt
• E. a base that forms when an acid loses a proton

Answer 1

The correct option is A a substance that can act as both acids and base by being both proton acceptor and proton donor

An amphoteric substance is a substance that can act as both acids and base by being both proton acceptor and proton donor.

Thus the bicarbonate ion $HC{O}_3^{-}$ is an amphoteric substance.

$HC{O}_3^{-}\to C{O}_3^{2-}+H^{+}$ (bicarbonate ion as an acid)

$HC{O}_3^{-}+H^{+}\to H_{2}C{O}_3$ (bicarbonate ion as a base)

Hence, the correct option is A.