If a lather is not obtained when performing a soap hardness test, the water sample is:

When performing a soap hardness test, the primary goal is to assess the presence of calcium and magnesium ions in the water sample. These ions are responsible for water hardness and prevent soap from lathering effectively. If a lather is not obtained during the test, it indicates that the water contains a significant concentration of these hardness-causing minerals. Therefore, the absence of lather strongly suggests that the water sample is hard, as the soap molecules are unable to form lather due to the interference caused by the calcium and magnesium ions.

In contrast, soft water has fewer or no hardness ions present, resulting in abundant lather formation when soap is introduced. Neutral water doesn't specifically relate to the hardness but typically implies no remarkable chemical properties like those seen in either hard or soft water. Contaminated water could have varied properties but does not directly correlate to the specific condition of lathering observed in the soap hardness test. Thus, the behavior of the water sample when soap is applied is a critical indicator of its hardness level.