Four students were asked to test a solution for the presence of a cation by using various anions - HSC - SSCE Chemistry - Question 15 - 2001 - Paper 1

To determine which student had results consistent with the conclusion that Pb²⁺ is present, we must analyze the precipitate results for each anion:

1. Chloride: Lead(II) chloride (PbCl₂) is soluble in water, so a precipitate indicates the absence of Pb²⁺.
2. Sulfate: Lead(II) sulfate (PbSO₄) is an insoluble salt, so a precipitate confirms the presence of Pb²⁺.
3. Carbonate: Lead(II) carbonate (PbCO₃) is also insoluble, so a precipitate also confirms the presence of Pb²⁺.

Now let's evaluate each student's results:

• Student A: No precipitate for chloride, no precipitate for sulfate, precipitate for carbonate (inconsistent)
• Student B: Precipitate for chloride, no precipitate for sulfate, no precipitate for carbonate (inconsistent)
• Student C: Precipitate for chloride, precipitate for sulfate, precipitate for carbonate (consistent)
• Student D: No precipitate for chloride, precipitate for sulfate, no precipitate for carbonate (inconsistent)

Based on this analysis, Student C had results that are consistent with the conclusion that Pb²⁺ is present.