The addition of a strong acid like hcl to an aqueous solution would result in

The addition of a strong acid like HCl to an aqueous solution would result in the decreasing of pH. Solution becomes more acidic.

Explanation:

HCl dissociates in water as this:

HCl → H⁺ + Cl⁻

Imagine and aqueous solution of NaCl where you have:

NaCl → Na⁺ + Cl⁻

2H₂O ⇄ H₃O⁺ + OH⁻

The addition of HCl would increase the [H₃O⁺]

2H₂O ⇄ H₃O⁺ ↑ + OH⁻

If the [H₃O⁺] is higher, the pH would be lower so the solution would be more acidic