Question

In graphite , the layers of carbon atoms are held by :
A.covalent bonds
B.coordinate bonds
C.van der Waals forces
D.ionic bonds

Answer 1

Hint: Graphite is an allotrope of carbon . Allotropes are different structural modifications of an element , which have different physical properties but identical chemical properties .

Complete step by step answer:
Graphite is a naturally occuring allotrope of carbon and it can also be manufactured artificially .
In graphite the carbon atoms are $s{p}^2$ - hybridised . Each carbon atom is linked to three other carbon atoms forming hexagonal rings . Thus , graphite has a two - dimensional sheet like layered structure consisting of benzene rings fused together . The successive layers in graphite are held together by weak forces of attraction and so one layer can slip over the other which makes it soft . The distance between any two successive layers is $3.40A^{\circ }$ .
They are held by van der Waals forces of attraction .
Hence option C is correct .
Unlike diamond , graphite is soft and a good lubricating agent .
Since only three electrons of each carbon are used in making hexagonal rings in graphite , the fourth valence electron of each carbon is free to move , which makes graphite a good conductor of heat and electricity .

Therefore, we can conclude that out of the given four options, C is the correct option.


Note:Among all the allotropes of carbon , graphite is thermodynamically the most stable allotrope . Its standard enthalpy of formation is taken as zero $({\mathrm{\Delta }}_{f}H=0)$ , whereas the standard enthalpy of formation of other allotropes is not zero . The enthalpy of formation of diamond and fullerene are $1.98$ and $38.1kJmo{l}^{-1}$ respectively .