Question

Which of the following pair of reactants can undergo a displacement reaction under appropriate conditions?

Options

• MgSO₄ + Fe

• ZnSO4 + Fe

• MgSO₄ + Pb

• CuSO₄ + Fe

Answer 1

CuSO₄ + Fe

Explanation:

A displacement reaction can only occur if a more reactive free metal reacts with the salt solution of a less reactive metal. According to the metal reactivity series, the order of reactivity is Mg > Zn > Fe > Cu. Because iron (Fe) is more reactive than copper (Cu), it successfully displaces copper to form iron sulphate and solid copper:

\[\ce{Fe + CuSO4 -> FeSO4 + Cu}\]

In all the other options, the free metal (Fe) or (Pb) is less reactive than the metal in the compound (Mg) or (Zn), resulting in no reaction.