what principle involved in when pewrforming sublimation?

Answer 1

The word is performing. The principle involved is that for a substance, there is a curve on the pressure-temperature plot of its 3 phases of state, which defines the boundary between solid and gas. If one such point is P1, T1, if you heat the solid to a higher temperature than T1 at the pressure P1, or lower the pressure below P1 at temperature T1, the solid will pass directly to the gaseous state. For water, this occurs at pressures below 0.1 mm and temperatures below 0 deg C. For something like CO2, at atmospheric pressure, the temperature is about -40 deg C.