JEE Advanced · 2011 · 10 Apr 2011 · Paper 1 · d and f Block Elements

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

Answer: (B)

Solution

The metal rod is copper (Cu). When Cu is dipped in

AgNO_{3}

solution, a displacement reaction occurs:

Cu + 2 AgNO_{3} \to Cu (NO_{3})_{2} + 2 Ag

The solution turns light blue due to the formation of

Cu^{2 +}

ions. This confirms that the metal rod is copper.

JEE Advanced · 2011 · 10 Apr 2011 · Paper 1 · Single correct option