Question

What will happen if a small amount of hydrochloric acid is added to a 0.1 m solution of hf?

Answer 1

pH will go down (become more acidic)

Step-by-step explanation:

This is because HCl is strong acid that means it dissociates completely into H+ and Cl- ions. There's already some H+ ions in solution contributed by HF but addition of HCl supplies more H+ which drives the pH of solution down making the solution more acidic.