According to the typical behavior of gases in relation to solubility:
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For pressure: The solubility of a gas in a liquid increases as pressure increases. This relationship is often described by Henry's Law.
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For temperature: The solubility of a gas in a liquid typically decreases as temperature increases. This is in contrast to solids, where solubility usually increases with temperature.
Given this understanding, let's analyze the options:
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A. both temperature and pressure are increased: This would likely lead to decreased solubility, since increasing temperature generally decreases gas solubility.
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B. both temperature and pressure are decreased: Decreasing pressure would decrease solubility, and decreasing temperature might increase solubility slightly, but the overall effect would be uncertain.
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C. the temperature is increased and the pressure is decreased: This option would decrease solubility since both an increase in temperature and a decrease in pressure are both conditions that decrease gas solubility.
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D. the temperature is decreased and the pressure is increased: Decreasing temperature would increase the solubility of the gas, while increasing pressure would also enhance solubility.
Therefore, the correct answer, according to the graphs, is:
D. the temperature is decreased and the pressure is increased.