Question

Why the grasses are covered with frost but the concrete sidewalk isn't

Answer 1

Answer:

Ground temperature does not vary much overnight, and so neither does the temperature of the concrete. ... When the temperature of the air plummets, so does that of the grass. And as we'll learn later, cooler temperatures make water more readily condense out of the air - forming dew on the cold blades of grass.

Answer 2

Answer:

as grass have process of transpiration whereas concrete does not