Which of the following pairs will give displacement reactions ?

Explanation

In a displacement reaction, a more reactive metal displaces a less reactive metal from the solution of its salt. Copper (Cu) is more reactive than silver (Ag). Therefore, when copper metal is placed in a silver nitrate (AgNO₃) solution, copper displaces silver and copper nitrate, [Cu(NO₃)₂], is formed. Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag Hence, the reaction between AgNO₃ solution and copper metal is an example of a displacement reaction. Copper (Cu) is less reactive than sodium; therefore, it cannot displace sodium from sodium chloride (NaCl) solution. Copper (Cu) and silver (Ag) are both less reactive than iron (Fe); therefore, they cannot displace iron from iron sulphate (FeSO₄) solution. Aluminium (Al) is less reactive than magnesium (Mg); therefore, it cannot displace magnesium from magnesium chloride (MgCl₂) solution.