The student clearly stated the independent variable as the solution's pH and the dependent variable as the absorbance of copper(II)-caffeine complexes. The research question included a detailed method of analysis, specifying the use of UV-Vis spectrophotometry to assess complex stability. The background theory was comprehensive, linking relevant concepts to the investigation, but the explanation of the absorbance measurement technique lacked clarity and detail regarding calibration and wavelength selection. The student effectively discussed the sampling technique, controlled variables, safety, ethical, and environmental issues, while providing a sufficiently detailed methodology that allowed for reproducibility without irrelevant information.
