Q. Which of the following pairs will give displacement reactions ?

Correct Answer: a) AgNO3 solution and copper metal

Explanation: Displacement reactions occur when a more reactive metal displaces a less reactive metal from its compound (usually a solution of its salt). The reactivity of metals is determined by their position in the reactivity series.

1. a) AgNO3 solution and copper metal:

Copper is more reactive than silver. Therefore, copper will displace silver from silver nitrate (AgNO3) solution, forming copper nitrate (Cu(NO3)2) and silver metal.

Reaction:

Cu(s) + 2AgNO3(aq) → Cu(NO3)2(aq) + 2Ag(s)

This is a displacement reaction.

2. b) NaCl solution and copper metal:

Copper is less reactive than sodium. Hence, copper cannot displace sodium from sodium chloride (NaCl) solution. No reaction occurs.

3. c) FeSO4 solution and silver metal:

Silver is less reactive than iron. Therefore, silver cannot displace iron from iron sulfate (FeSO4) solution. No reaction occurs.

4. d) MgCl2 solution and aluminium metal:

Aluminium is less reactive than magnesium. Hence, aluminium cannot displace magnesium from magnesium chloride (MgCl2) solution. No reaction occurs.