Answer
Physical change
Work Step by Step
Physical change: the substance stays the same chemically ($H_2O$ before and after).
Chemical change: the substance’s chemical composition would change (new substances formed).
Here, snow (which is solid $H_2O$) becomes water vapor (gaseous $H_2O$) with no change in composition. Therefore sublimation of snow is a physical change because the substance remains $H_2O$ - only its physical state changes, not its chemical identity.
