Which one of the following chemical reactions is not feasible?

The feasibility of a single displacement reaction depends on the metal reactivity series. A more reactive metal can displace a less reactive metal from its salt solution. According to the activity series, the order of reactivity is Magnesium (Mg) > Zinc (Zn) > Iron (Fe) > Lead (Pb) > Copper (Cu) [2]. In options 1, 2, and 4, Fe, Zn, and Mg are all more reactive than Copper, allowing them to successfully displace Cu from CuSO4. However, in option 3, Copper (Cu) is less reactive than Lead (Pb) [2]. Consequently, Copper cannot displace Lead from PbCl2, making this reaction non-feasible. This is further supported by standard reduction potentials, where metals with lower reduction potentials (more negative) act as stronger reducing agents and displace those with higher potentials.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.2.5 The Reactivity Series > p. 45
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.4.1 Extraction of Metals > p. 50