Aqueous solutions of which ion give a reddish precipitate when excess hydroxide ion is added?
A. [tex] \text{Cu}^{2+} [/tex]
B. [tex] \text{CO}_3^{2−} [/tex]
C. [tex] \text{Fe}^{3+} [/tex]
D. [tex] \text{Al}^{3+} [/tex]
E. [tex] \text{Pb}^{2+} [/tex]
Answer (2)
Fe ^3+ is the correct answer
The ion that gives a reddish precipitate when excess hydroxide ions are added is \text{Fe}^{3+}, forming iron(III) hydroxide, \text{Fe(OH)}_3. Other options like \text{Cu}^{2+}, \text{Al}^{3+}, and \text{Pb}^{2+} do not produce reddish precipitates. Hence, the correct choice is C: \text{Fe}^{3+}.
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