What must be done to coal before it can be used as fuel? It must be made to stick together.
It must be compressed into a very dense substance.
It must be ground into powder.
It must have flammable material added to it.

It must be ground into powder.

Explanation:

"Coal" is one of the nonrenewable resources that humans use for fuel. In order to produce energy, it needs to be burned first. However, efficient combustion happens when the coal is pulverized into fine powder first. This allows the coal to mixed with hot air sufficiently in order to release heat. This then allows the "generation of electricity" that is often used for cooking, lighting, cooling, transportation, healthcare, etc.

i'm guessing this is from edg enuity so the answers would be, from top to bottom,

theodor schwann

matthias schleiden

robert hooke

rudolph virchow

anton van leeuwenhoek

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.