(i) On industrial scale it is produced by burning coke in excess of air
2CO + O₂ ⟶ 2CO₂ [H = 394 kJ mol^-1]
(ii) Calcination of lime produces carbon dioxide as by product.
CaCO₃ ⟶ CaO + CO₂

(i) Graphene is an allotropic form of carbon.
(ii) It has a single planar sheet of sp² hybridised carbon atoms that are densely packed in a honeycomb crystal lattice.

(i) Fullerenes are newly synthesised allotropes of carbon.
(ii) Unlike graphite and diamond, these allotropes are discrete molecules such as C_32' C_50' C_60' C_70' C₇₆ etc.
(iii) These molecules have cage like structures.
(iv) The C₆₀ molecules have a soccer ball like structure and is called buckminster fullerene or buckyballs.
(v) It has a fused ring structure consists of 20 six membered rings and 12 five membered rings.
(vi) Each carbon atom is sp² hybridised and forms three σ bonds & a delocalised π bond giving aromatic character to these molecules.
(vii) The C-C bond distance is 1.44 Å and C=C distance 1.38 Å.

(i) Graphite is the most stable allotropic form of carbon at normal temperature and pressure.
(ii) It is soft and conducts electricity. It is composed of flat two dimensional sheets of carbon atoms.
(iii) Each sheet is a hexagonal net of Sp² hybridised carbon atoms with a C-C bond length of 1.41 Å which is close to the C-C bond distance in benzene (1.40 Å).
(iv) Each carbon atom forms three a bonds with three neighbouring carbon atoms using three of its valence electrons and the fourth electron present in the unhybridised p orbital forms a π-bond.
(v) These π electrons are delocalised over the entire sheet which is responsible for its electrical conductivity.
(vi) The successive carbon sheets are held together by weak van der Waals forces. The distance between successive sheet is 3.40 Å.
(vii) It is used as a lubricant either on its own or as a graphited oil.

(i) Aluminium chloride is obtained by heating a mixture of alumina and coke in a current of chlorine.
Al₂O₃ + 3C + 3Cl₂ ⟶ 2AICl₃ + 3CO₂
(ii) On industrial scale it is prepared by chlorinating aluminium around 1000 K.
2Al + 3Cl₂ \(\overset { 1000K }{ \longrightarrow } \) 2AICl₃