The group II reagent in the cation analysis is the dil.HCl + H₂S. The role of dil.HCl is

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

To decrease $[S^{2 -}]$ and so increase the ionic product to exceed the $K_{Sp}$ of group IV sulphides and prevent their precipitation.

To dissolve group II metal sulphides in acid medium

To decrease $[S^{2 -}]$ concentration so that the ionic product of only group II sulphides exceed their K_sp values

answer is A.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

$H_{2} S ⇌ 2 H^{+} + S^{2 -}, HCl \to H^{+} + {Cl}^{-}$
Due to common ion effect $[H^{+}] [S^{2 -}]$ decreases. $K_{Sp}$ values of Group-II sulphides are less than Group-IV sulphides. The decreased concentration is sufficient to precipitate Gr-II cations, but not Group-IV cations.