Answer:
The concentration of H+ ions in an aqueous solution is determined by the strength of the acid. Strong acids dissociate completely in water, leading to the highest concentration of H+ ions, while weak acids dissociate only partially, resulting in a lower concentration of H+ ions.
Among the options given:
a. HCl (aq) - This is a strong acid and dissociates completely into H+ and Cl- ions in water, resulting in the highest concentration of H+ ions.
b. H2SO4 (aq) - This is also a strong acid, as it dissociates almost completely in water to produce two H+ ions and one sulfate ion (SO4^2-).
c. HBr (aq) - Like HCl, HBr is a strong acid and dissociates completely in water to form H+ and Br- ions.
d. H2CO3 (aq) - This is a weak acid (carbonic acid). It dissociates only partially in water to form H+ and HCO3- ions.
Therefore, the option that forms the lowest concentration of H+ ions in water is d. H2CO3 (aq), carbonic acid.
