Chapter 12, Problem 80A

Interpretation Introduction

Interpretation:

The reason for a pile of snow to slowly shrink even on days when the temperature never rises above the freezing point of water must be explained.

Concept introduction:

Formation of snow takes place when water vapor goes to high altitudes and condenses suddenly to solid without going through liquid.

Answer to Problem 80A

Pile of snow slowly shrinks due to sublimation.

Explanation of Solution

Sublimation is a process in which solid is converted to gas without the attainment of liquid state. Snow formation is a deposition process which is reverse of condensation process.

Formation of snow takes place at low temperature at higher altitude.

So at room temperature snow can sublime to water vapor without going through liquid water.

Conclusion

Pile of snow shrinks due to sublimation.