Answer:
The smallest unit of a compound is a molecule, which is made up of atoms held together by bonds.
Friction. It transforms other forms of energy into thermal energy
Answer:
A. Engineers come up with scientific questions when they are developing their design, and scientists do research to answer them.
Answer:
The outer core of the earth is liquid.
Explanation:
Seismic waves travel through the Earth at different speeds and are reflected and refracted diffracted differently as they encounter layers of different densities.
By analyzing these waves, they have concluded that there is an inner core of solid iron surrounded by a liquid outer core consisting of nickel and iron.
A is wrong. The Earth consists of several layers
C is wrong. Seafloor spreading is caused by the movement of tectonic plates away from each other.
D is wrong. The mantle is mostly solid rock.