Final answer:
Glycerin has the lowest vapor pressure at 75°C compared to the other substances like ethanol, water, and isobutene since it is described as nonvolatile at 40°C.
Step-by-step explanation:
The substance with the lowest vapor pressure at 75°C would be glycerin, based on the provided information. Glycerin is described as essentially nonvolatile at 40°C, which means its vapor pressure is very low compared to other substances listed at any given temperature.
While ethanol and substances like benzene and water have measurable vapor pressures at various temperatures, and isobutene has a specific vapor pressure at 50°C, the fact that glycerin is nonvolatile at 40°C suggests it would still have a very low or negligible vapor pressure at 75°C.
Therefore, compared to ethanol, water, benzene, isobutene, and various solutions mentioned, glycerin would likely have the lowest vapor pressure at the given temperature.
The substance with the lowest vapor pressure at 75°C is glycerin. Glycerin is essentially nonvolatile at this temperature, meaning it has a very low tendency to evaporate or vaporize. In contrast, other substances like ethanol and water have higher vapor pressures, meaning they have a greater tendency to vaporize at this temperature.