In which of the following reactions are two different atoms or groups of atoms (ions)
exchanged?

Correct option is B

The correct answer is (b) Double displacement.
· In a double displacement reaction, also known as a double replacement or metathesis reaction, two different atoms or groups of atoms (ions) are exchanged between two compounds.
· This reaction typically occurs in aqueous solutions where the ions in the reactants switch places to form two new compounds.
Example of Double Displacement Reaction:
AB+CD→AD+CB
For instance, when silver nitrate (AgNO₃) reacts with sodium chloride (NaCl), the ions are exchanged to form silver chloride (AgCl) and sodium nitrate (NaNO₃):
AgNO3+NaCl→AgCl+NaNO3