No reaction. You can know these reactions by the following:
Reactions that are not oxidation/reduction reactions, take place for one of the following reasons.
a. a ppt is formed. So a solubility table will tell you if the possible combinations are soluble or not.
b. a gas is formed. You know the common gases. H2, O2, N2, F2, Cl2, CO2, CO, SO2, and a few others.
c. a weak electrolyte is formed. You can determine if the material is a weak electrolyte or not by looking to see if it has a Ka or a Kb in a list of tables for Ka and Kb.
If one of these is NOT true, then there is no reaction. In your problem, the possible combinations are (for a double displacement) Li2SO4 and NH4Cl. Both of these are solids (not b), both are soluble in water (not a), and they are salts so they aren't listed in a Ka or Kb table. SO, the reaction will not go.