Question

Which molecule is amphoteric?

A) NH4+

B )H2O

C )H2CO3−

D )H2SO4

Answer 1

The answer is letter choice B

Answer 2

Answer: B )
`H_2O]`

Explanation:- According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.

Amphoteric substances are substances which can act as both acids and bases and thus can accept and donate
`H^+` ions.

`H_2O\rightarrow H^++OH^_`

Here water acts as an acid as it donates
`H^+` ions.

`H_2O+H^+\rightarrow H_3O^+`

Here water acts as a base as it accepts
`H^+` ions.