Qualitative Analysis - Result Question 35
Passage
When a metal rod $M$ is dipped into an aqueous colourless concentrated solution of compound $N$, the solution turns light blue. Addition of aqueous NaCl to the blue solution gives a white precipitate $O$. Addition of aqueous $\mathrm{NH}_3$ dissolves $O$ and gives an intense blue solution.
(2011)
38. The metal rod $ M$ is
(a) $Fe$
(b) $Cu$
(c) $Ni$
(d) $Co$
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Answer:
Correct Answer: 38. (b)
Solution:
Appearance of blue colour on addition of the metal $\operatorname{rod} M$ to the solution of $N$ is an indication that metal may be $Cu$. Later formation of white precipitate on addition of $NaCl$ and dissolution of this precipitate in aqueous ammonia confirm that while precipitate is of $AgCl$. This implies that the solution $N$ is of $AgNO _3$. This confirm that the metal $M$ is only $Cu$.
BETA
