Which of the following cations is NOT precipitated by passing gas in a dilute acidic medium? — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

$Pb^{2+}, Sn^{2+},$ and $Cu^{2+}$ belong to Group II and have very low $K_{sp}$ values, hence they precipitate as sulphides in acidic medium. $Ni^{2+}$ belongs to Group IV; its sulphide has a higher $K_{sp}$ and only precipitates in a basic medium.