Which of the following statement/s is/are correct about weak acids in aqueous solutions?
I. When $$pH = pK_a$$ of a monoprotic acid, 50% of the acid is ionised
II. If $$pH = pK_{a2}$$ of a diprotic acid, the average charge of all the ionised species is 0.5
III. When $$pH = pK_a + 1$$, 10% of the acid is ionised
IV. When $$pH = 7$$, 50% of a monobasic acid is ionised

A

I and IV

B

I, II and IV

C

Statements I, II and IV

D

I only