A. Sodium acetate + Ammonium sulphate
The balanced chemical reaction would be:
2 CH3COONa (aq) + (NH4)2SO4 (aq) --> 2 CH3COONH4 (aq) + Na2SO4 (s)
Na2SO4 is a salt and will precipitate out in normal conditions. Therefore yes there is a precipitate.
B. Calcium chloride + Mercury(i) Nitrate
The balanced chemical reaction would be:
CaCl2 (aq) + 2 HgNO3 (aq) --> 2 HgCl (aq) + Ca(NO3)2 (aq)
All product are soluble and therefore there is no precipitate.