Final answer:
After the reaction between sodium sulfide and cadmium nitrate, assuming sodium sulfide is the limiting reactant, sodium nitrate and cadmium sulfide will be present in the test tube, with cadmium sulfide as a precipitate and sodium nitrate in solution.
Step-by-step explanation:
The reaction in question is a double replacement reaction where sodium sulfide (Na2S) reacts with cadmium nitrate (Cd(NO3)2) to produce sodium nitrate (NaNO3) and cadmium sulfide (CdS). Since sodium sulfide is stated as the limiting reactant, after the reaction has completed, there will no longer be any Na2S present in the test tube.
The substances found at the end of the reaction will be sodium nitrate (NaNO3), which is soluble and remains in the aqueous solution, and cadmium sulfide (CdS), which is insoluble and precipitates out of the solution as a solid. Any remaining cadmium nitrate (Cd(NO3)2) will also be present if it was in excess.