Answer: B. False
Explanation: A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
Example:
Thus as we can see sodium ion
is being replaced by ammonium ions
and thus positive ions replace positive ions only and not negative ions.