This layer of Earth is divided into two sections, both of which primarily contain silicate minerals. Part of one of the sections is able to flow like a thick fluid. What is this layer known as?

The layer is known as crust.

Explanation:

The inner layer or the core of Earth is composed of different layers. Those layers are composed of minerals, rocks, sands and crusts.  Basically, the tough layer is termed as crust of the Earth which contains the tectonic plates and silicate minerals in it.

Even it contains a thick juicy fluid like behavior in case of much heated regions. The two divisions of the crusts are termed as inner crust and the outer crust. The inner crust contains the juicy thick fluid because of high temperature and the outer crust is composed of silicate minerals. Hence, the layer is known as crust.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.