Answer and Explanation:
Lithosphere is composed of earth crust and upper portion of the mantle or the outer most layer which behaves as rigid and brittle solid. The thickness of Lithosphere is about 100 km whereas, Asthenosphere is the solid layer of the upper mantle which due to its extremely high temperature can flow. Thus the constituents solid rocks of asthenosphere of which it is made up of, under high temperature and high pressure behaves like liquid.
Thus in order to understand the concept in a clear way we say that lithosphere floats on asthenosphere which is technically an incorrect statement as both the layers are solid.