The pair(s) of ions where BOTH the ions are precipitated upon passing H₂S gas in presence of dilute HCl, is(are)
- (A)Ba²⁺, Zn²⁺
- (B)Bi³⁺, Fe³⁺
- (C)Cu²⁺, Pb²⁺✓ Correct
- (D)Hg²⁺, Bi³⁺✓ Correct
Answer: (C), (D)
Solution
In qualitative analysis, Group II cations (Cu²⁺, Pb²⁺, Hg²⁺, Bi³⁺, Cd²⁺, As³⁺, Sb³⁺, Sn²⁺) are precipitated as sulfides in acidic medium (dilute HCl + H₂S).
(A) Ba²⁺ is Group V (not precipitated by H₂S); Zn²⁺ is Group IV (precipitated in basic medium). Incorrect.
(B) Bi³⁺ is Group II (precipitated); Fe³⁺ is Group III (not precipitated in acidic H₂S). Incorrect.
(C) Both Cu²⁺ and Pb²⁺ are Group II cations, precipitated as CuS and PbS. Correct.
(D) Both Hg²⁺ and Bi³⁺ are Group II cations, precipitated as HgS and Bi₂S₃. Correct.
Correct options: (C) and (D).
(A) Ba²⁺ is Group V (not precipitated by H₂S); Zn²⁺ is Group IV (precipitated in basic medium). Incorrect.
(B) Bi³⁺ is Group II (precipitated); Fe³⁺ is Group III (not precipitated in acidic H₂S). Incorrect.
(C) Both Cu²⁺ and Pb²⁺ are Group II cations, precipitated as CuS and PbS. Correct.
(D) Both Hg²⁺ and Bi³⁺ are Group II cations, precipitated as HgS and Bi₂S₃. Correct.
Correct options: (C) and (D).
JEE Advanced · 2015 · 24 May 2015 · Paper 2 · One or more correct options