Sample A is 100. mL of a clear liquid. The density of the liquid is measured, and turns out to be 0.77 g/mL. The liquid is then cooled in the refrigerator. At 10.0 °C two separate clear layers form in the liquid. When the temperature is raised back to room temperature, the layers disappear. Sample B is a solid yellow cube with a total mass of 50.0 g. The cube is divided into two smaller 25.0 g subsamples, and the minimum volume of water needed to dissolve each subsample is measured. The first subsample just barely dissolved in 101. mL of water, the second in 92.0 mL. When the experiment is repeated with a new 50.0 g. sample, the minimum volume of water required to dissolve the two subsamples is 89.0 mL and 93. mL.

Required:
a. Is sample A made from a pure substance or a mixture?
b. Is sample B made from a pure substance or a mixture?