Among the following cations, the number of cations which will give characteristic precipitate in their identification tests with $ ext{K}_4[ ext{Fe(CN)}_6]$ is ______. $ ext{Cu}^{2+}, ext{Fe}^{3+}, ext{Ba}^{2+}, ext{Ca}^{2+}, ext{NH}_4^+, ext{Mg}^{2+}, ext{Zn}^{2+}$

Question

Among the following cations, the number of cations which will give characteristic precipitate in their identification tests with $	ext{K}_4[	ext{Fe(CN)}_6]$ is ______. $	ext{Cu}^{2+},	ext{Fe}^{3+},	ext{Ba}^{2+},	ext{Ca}^{2+},	ext{NH}_4^+,	ext{Mg}^{2+},	ext{Zn}^{2+}$

Dr. Abubacker · Accepted Answer

[Solution by Dr. Abubacker] $	ext{Cu}^{2+}$ gives a chocolate-brown precipitate ($	ext{Cu}_2[	ext{Fe(CN)}_6]$), $	ext{Fe}^{3+}$ gives Prussian blue, and $	ext{Zn}^{2+}$ gives a white/bluish-white precipitate ($	ext{Zn}_2[	ext{Fe(CN)}_6]$). The others do not give a characteristic precipitate in their standard identification tests. Count $=3$. (Medium confidence: answer follows the official key.) Answer: 3.

Q. Among the following cations, the number of cations which will give characteristic precipitate in their identification tests with $\text{K}_4[\text{Fe(CN)}_6]$ is ______. $\text{Cu}^{2+},\text{Fe}^{3+},\text{Ba}^{2+},\text{Ca}^{2+},\text{NH}_4^+,\text{Mg}^{2+},\text{Zn}^{2+}$

Explanation

Reviewed by Dr. Abubacker

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