Which of the following is a Brønsted-Lowry base?

A - HCl

B - HCO

C - H3O+

D - H3PO4

C. H₃O⁺ is a Bronsted Lowry base.

Explanation:

Any substance that accepts hydrogen ions or (H⁺) ions or protons during any chemical reaction is termed as a Bronsted Lowry base.

Here HCl donates a proton so it is not a Bronsted Lowry base.

HCO is also not a Bronsted Lowry base.

H₃O⁺ is a Bronsted Lowry base because it accepts H⁺ ion from one of its reactant.

H₃PO₄ is also not a Bronsted Lowry base.

So option C. H₃O⁺ is a Bronsted Lowry base.