In the equation hcl (g) + h2o (l) ® h3o + (aq) + cl - (aq), which species is a brønsted-lowry acid?

a. hcl

According to Bronsted-Lowery Concept, An Acid is a specie which can donate H⁺ and Base is a specie which tends to accept H⁺.

In equation given as,

HC l ₍g₎ + H ₂O ₍l₎ → H₃O⁺ ₍aq₎ + Cl ⁻ ₍aq₎

In this reaction HCl is loosing proton and converting into conjugate base Cl⁻ and H₂O is accepting proton and converting into conjugate base H₃O⁺.

Result:

Acid = HCl

Base = H₂O