ou observed isopropanol and water drops on a paper towel. Even though the same amount of energy was transferred into both substances from the air, the isopropanol evaporated while the water did not. Why do you think the isopropanol changed phase, but the liquid water did not?

The Isopropanol had a lower heat of vaporization than that of water, meaning that it didn't have to have as much energy to accomplish a phase change, in this case evaporation.

you must remain stopped until the stop signal is retracted and the red lights are turned off. approaching traffic in the opposite roadway of a divided highway shall not be required to stop, even if the school bus has the stop-arm extended and the alternately flashing warning signal lamps on.