1. Tardigrade
  2. Question
  3. Chemistry
  4. 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 NH3 dissolves O and gives an intense blue solution. The metal rod M is (1) Fe (2) Cu (3) Ni (4) Co

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Q. 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 $NH_3$ dissolves $O$ and gives an intense blue solution.
The metal rod $M$ is
(1) $Fe$
(2) $Cu$
(3) $Ni$
(4) $Co$

IIT JEEIIT JEE 2011Organic Chemistry – Some Basic Principles and Techniques

Solution:

Appearance of blue colour on addition of the metal 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 $Cu$.