I think the correct answer from the choices listed above is option B. The reactants calcium sulfide and sodium sulfate will react and form a precipitate which is calcium sulfate since it is only slightly soluble in aqueous solution. Hope this answers the question.
The answer is A :) your welcome hope this helps
Answer:
It is mentioned that the student is mixing chemicals A and B and observes the time taken for the color to change. However, in the experiment, it is noticed that the student has repeated the procedure five times and each time he or she is modifying the concentration of chemical B. Thus, it is clear that the concentration of chemical B is the independent variable in the experiment. An independent variable is illustrated as the variable, which is controlled or modified in the experiment.
Density = mass/volume = 2000/4000 = 0.5 grams/cm3. Hope this hopes!
