Question

Which of the following solutions with same concentrations will have lowest pH? (a) H2SO4 (b) HCOOH (c) CH3COOH (d) H2CO3

Answer 1

it's carbonic acid. Rest all hv pH higher than H2CO3.

Answer 2

Thank you for asking this interesting question.
i will help you out in finding the answer.
The answer is that H2CO3 is a weak acid as compares to other mentioned acid.
H2CO3 or carbonic acid is the weak acid because it don't completely dissociates and partially dissociated into ions in a aqueous medium . So there are few hydrogen ions formation this is why  carbonic acid is a weak acid.
I hope this will help you.