From the diagram above describing the phase of water relative to temperature and pressure, is it possible for ice to transform to water vapor (sublime)without ever becoming liquid? At which point on the diagram does this occur?

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Quizplus · Accepted Answer

At point D, which is below the triple point, ice can sublime without first becoming liquid. This process is called sublimation, and it occurs when a substance goes directly from a solid to a gas without passing through the liquid phase. Water can be made to sublime at low pressures, as is the case in freeze-drying, a common technique for preserving food and pharmaceuticals.

From the Diagram Above Describing the Phase of Water Relative