Which of these reactions can be classified as double replacement reactions?

A) Zn + 2HCl → ZnCl2 + H2

B) 2NaCl + F2 → 2NaF + Cl2

C) 2AlBr3 + 3K2SO4 → 6KBr + Al2 (SO4) 3

D) 2K + MgBr2 → 2KBr + Mg

C is the answer. Reasons being that, two elements from both side of the reactant switches side to form two new compounds. On the other hand, A, B and D involves one element displacing the other to produce a new compound.