What happens when the pressure is increased from 50 kPa to 150 kPa.on an ice cube at 0^circ C according to this phase diagram of water? The ice cube melts. The ice cube sublimes. The ice cube remains solid.

To answer this question, we need to understand the phase diagram of water. A phase diagram shows the preferred physical states of matter at different temperatures and pressures. In the phase diagram of water, the line that separates the solid phase (ice) from the liquid phase (water) has a negative slope. This means that as pressure increases, the temperature at which water can exist as a solid decreases. At , water can exist as ice at normal atmospheric pressure (approximately ). If the pressure is increased while the temperature is held constant at , we move vertically up on the phase diagram. Due to the negative slope of the solid-liquid boundary, an increase in pressure will cross this boundary from the solid region into the liquid region, indicating that the ice will melt into water.