Please answer this question with complete explanation.

Dear student

H₂S will dissociate into H⁺ and S^-2. For highly acidic medium, let take HCl, HCl will dissociate into H⁺ and Cl^-. Due to common ion effect of H^{+ ,} reaction will proceed in backward direction and as a result concentration of S^-2 ion decreases, it will not combine with Cd⁺² in appropriate amount and therefore will not precipitate .

WITH REGARDS 

MAHIMA 

ASKIITIANS FORUM EXPERT