Passage V
Students studied the photodecomposition (breakdown by light) of p-nitrophenol (a toxic pollutant) in wastewater. They measured the concentration of p-nitrophenol (in parts per million, ppm) in wastewater samples during exposure to various lighting conditions. Titanium dioxide (TiO2) and/or hydrogen peroxide (H2O2) were added to some samples at the start of exposure (time = 0 min). TiO2 and H2O2 speed up some photodecomposition reactions. The results of 3 sets of experiments are shown in Figures 1-3.
23. According to Figure 1, 60 min after TiO2, was added to the wastewater sample that was NOT exposed to sunlight, the concentration of p-nitrophenol was closest to which of the following?
Your Answer is
Correct Answer is C
Explanation
Look at figure 1, when the abscissa is 60 min, the ordinate of TiO2, no sunlight line is about 2.5 ppm