Question

What is the molarity of hydrogen ions in a 2.7M solution of the strong acid HCl?

Answer 1

strong acids dissociate completely, so if you started with 2.7M HCl, and all of it dissociated, you'd have \[HCl \leftrightharpoons H^+(aq) + Cl^-(aq) \]\["0" \space \space \space \space 2.7M \space \space \space \space \space \space \space \space 2.7M\]