Answer :

Diamond structure is tetrahedral, where each carbon atom is bonded tetrahedrally to four other carbon atom. This makes it the hardest natural substance. The bond angles are 109 28'. 

Graphite is bonded to three other carbon atoms at an angle of 120 degrees. It is in layers which allows them to slow over each other which is why it is used in pencils. Graphite has a delocalised system of electrons. Because of this it allows graphite to conduct electricity along the layers but not in a direction of a right angle to the layers.

Graphite:

i) Inside the each layer of Graphite, The free electrons movies continuously. Due to which, Graphite is a good conductor of electricity.

ii) Graphite is found in nature as free state is black, Slippery and Brittle.

iii) Density of Graphite is .9 to 2.3g/cm^3

iv) Graphite is mostly used in making all leads and extract of writing pencils.

v) Like diamond, Graphite also doesn't dissolve in any solvent.

Diamond:

i) Density of Diamond is 3.5g/cm^3

ii) Melting point of diamond is 3500 degree Celsius.

iii) There is no effect of Acids and bases on diamond.

iv) Diamond doesn't dissolve in any solvent.

v) Diamond is bad conductor of electricity; As it does not have free electrons.

vi) When diamond is heated at 800 degree Celsius in presence of oxygen, then only it released the CO2.

Uses of Diamond:

i)  Diamond is used in ornaments and decoration.

ii) Diamond is used for Glass cutting and rock drilling machines.

iii) Diamond is used in making eye surgery knives.

iv) Diamond dust is used for polishing of other diamonds.

v) Diamonds is used in Space-crafts and Satellites to prevent radiations.

Uses of Graphite:

i)    Graphite is used in writing pencils and Lead of Lead pencils.

ii)   Graphite is used in making of Lubricants and Light bulbs.

iii)  Graphite is used for making Carbon electrodes.

iv)  Graphite is uses in Arc lamps to make the light more brighter and effective.

v)   Graphite is used in paints and polish to give a better look.

"By considering points of Diamond and Graphite, You can compare/differ between Diamond and Graphite. "

Q. Graphite is utilized in making electrodes due to following properties:

i) Good conductor of Electricity

ii) Keeps the surface look always clean and rough

iii) It is inexpensive; It saves expenses

iv) Insoluble in water, Acids and Bases

v) Have High density

Q. Why Diamond, Silver, Platinum are used in making jwelleries ? :

Gold, Silver, Platinum are used for making Jwelleries. Because they are very precious. And, Only Rich people can afford it. So, Gold, silver, platinum , diamond is used in Jwelleries. As well as, they don't have effect of surrounding and environment. And, it also prevents Ornaments from rusting.

Diamonds are used for making jwelleries because, Diamond is one of the rarest substance found in nature. As it is so Hard and expensive, so only rich people can afford it. Therefore, Diamond is used for making Jwelleries.