If addition of a substantial quantity of acid to a solution

If addition of a substantial quantity of acid to a solution resulted in only a moderate change in the pH of the solution, which of the following is likely true? a) The solution was pure water before the acid was added. b) The solution contained a buffer. c) The solution was strongly basic before the acid was added. d) The solution contained a moderate concentration of H+ before the acid was added. e) There is more than one correct answer choice.

Solution

Ans . E

There are 2 possible choices either the solution contained buffer, that is why it tried to normalise the ph back to its original when acid was added but it could not so only moderate increase in ph was observed.

or the soluion already contained a strong base, so when acid was added, it tried neutralising it, and only a small change in ph was observed