The easiest way to go about solving solubility problems is to examine the solubility rules
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So, starting with mercury (I) chloride, or Hg_2Cl_2. As you can see, you're dealing with a halide or, more specifically, with a chloride. Notice that all halides are soluble with the exception of those formed with three cations, including Hg^(2+).
As a result, mercury (I) chloride will be insoluble in water.
Use the same approach for all the compounds listed.
Sodium sulfide, or Na_2S, is soluble in water because all compounds that contain the sodium cation, Na^(+), are soluble in water. The same is true for compounds that contain the ammonium ion, NH_4^(+), so ammonium phosphate, (NH_4)_3PO_4 is soluble in water.
Cadmium carbonate, CdCO_3, and lead (II) sulfate, PbSO_4, are both insoluble in water because they do no represent soluble exceptions for compounds formed with the carbonate, CO_3^(2-), and phosphate, PO_4^(3-) anions.
