1)

When a metal rod M is dipped into an aqueous colourless concentrated solution of compound N, the solution turns light blue. The 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


A) Fe

B) Cu

C) Ni

D) Co

Answer:

Option B

Explanation:

The appearance of blue colour on the 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 confirms that the metal M is only Cu