Which oen among the following pairs of ions cannot be separated by H base 2S in dilute hydrochloric acid?

a. Bi^3+, Sn^4+

b. Al^3+, Hg^2+

c. Zn^2, Cu^2+

d. Ni^2+, Cu^2+

(a) NOTE : The ions of group II of salt analysis are precipitated by HCI and H base 2S whereas members of group IV are precipitated by H base 2S in alkaline medium.

? Bi^3+ and Sn^4+ both belong to group II

? They will be precipitated by HCI in presence of H base 2S.

Both Bi^3+ and Sn^4+ belong to group II of qualitative inorganic analysis and will get precipitated by H base 2S.