arbon, as with many elements, can arrange its atoms into several different geometries, or "allotropes." In pure diamond, every carbon atom is covalently bonded to exactly 4 other carbon atoms in a very specific and energetically favorable geometry. The diamond cannot be broken or scratched unless many covalent bonds are broken, which is difficult to do. In another common allotrope, graphite, every carbon atom is covalently bonded to only 3 other carbon atoms, and the atoms are arranged in sheets that are not covalently bonded to each other. The sheets can be broken apart easily, ultimately meaning that graphite can be easily scratched. Coal is composed of particles of different allotropes of carbon, and some "amorphous carbon," which has no defined geometry in its atomic structure. Without a continuous network of covalent bonds, coal is easily scratched (i.e. it is not hard).
If the comet were to strike the planet, the impact energy would be about 300 times that of the asteroid collision that was thought to have caused the Cretaceous-Tertiary extinction that killed the dinosaurs about 65 million years ago.
5a. the force moving object one place to the next 5b the force moving object without anything happening 5c the force moving a object and changing its position
The part of human body that do the same job as wires and circuits is our brain . With enormous amount of nerves and computing cells , our brain has the capacity to do work like circuits . ,Not equal to them , but to some extent its quite complex
