Which of the following pairs will give displacement reactions? (a) NaCl solution and copper metal (b) MgCl2 solution and aluminium metal (c) FeSO4 solution and silver metal (d) AgNO3 solution and copper metal

Solution: Option d i.e., AgNO₃ solution and copper is the correct answer. Copper displaces the silver cations (reducing them to the elemental metal), in the process copper itself is being oxidised to Copper II cations (Cu²⁺) and going into solution. So silver metal is seen precipitating out and a copper II nitrate solution will remain.

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