Demonstrate Understanding of Important Components of Scientific Research Practice Test

A physical chemistry lab tests the hypothesis that decreasing pH increases the solubility of a weak base drug by increasing its protonated (charged) fraction. Two buffered solutions are prepared at 25°C with identical total drug amount added and identical ionic strength; the only condition changed is pH (pH 2 vs pH 7). After equilibration and filtration, dissolved drug concentration is measured: pH 2 = 8 mM; pH 7 = 1 mM. Which factor most likely influences the outcome observed in this study?

A materials science group tests the hypothesis that adding a small amount of NaCl to water increases the electrical conductivity of the solution because it increases the concentration of mobile ions. Four beakers each contain 100 mL of deionized water at 25°C. A conductivity probe is calibrated, then inserted into each beaker after gentle stirring. The only condition changed is NaCl mass added. Results are recorded after the reading stabilizes.

Which hypothesis best aligns with the study's design?