Question

Which of the following cannot act both as Bronsted acid and as Bronsted base?

Options

• \[\ce{HSO^-_4}\]

• \[\ce{HCO^-_3}\]

• NH₃

• HCl

Answer 1

HCl

Explanation:

According to the Bronsted-Lowry theory, a substance must both donate and accept a proton to act as both an acid and a base. \[\ce{HSO^-_4}\] and \[\ce{HCO^-_3}\] can donate as well as accept protons, so they act as both Bronsted acids and bases. NH₃ acts as a base but can form \[\ce{NH^+_4}\], making it amphoteric. But HCl only donates a proton and cannot accept one, so it acts only as a Bronsted acid, not a base.