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).
Answer: Option C.
C)the tails of plant lipids cannot pack as tightly together as animal ones
Explanation:
The tails of plant lipids cannot pack as tightly together as animal ones because the double bond in plant lipids make the hydrocarbon chains to bend making them no to pack tightly together which cause a reduction in van der Waals interaction between the fatty acids. The length of the double bond also affect the melting point of fatty acids . If the hydrocarbon chain is long, melting point will be high .
