Choose the correct alternative :

(a) In a combined state, carbon occurs as

(i) coal

(ii) diamond

(iii) graphite

(iv) petroleum

(b) A crystalline form of carbon is

(i) lamp black

(ii) gas carbon

(iii) sugar

(iv) fullerene

(c) Graphite is not found in

(i) Bihar

(ii) Maharashtra

(iii) Orissa

(iv) Rajasthan

(d) Diamond is used for

(i) making the electrodes of electric furnaces.

(ii) making crucible for melting metals.

(iii) cutting and drilling rocks and glass.

(iv) making carbon brushes for electric motors.

(e) Carbon forms innumerable compounds because

(i) it has four electrons in its outermost shell.

(ii) it behaves as a metal as well as a non-metal.

(iii) carbon atoms can form long chains.

(iv) it combines with other elements to form covalent compounds.

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(a) In a combined state, carbon occurs as Petroleum.


  • Petroleum, also called crude oil, is a fossil fuel.
  • Like coal and natural gas, petroleum was formed from the remains of ancient marine organisms, such as plants, algae, and bacteria.
  • Petroleum consists mainly of hydrocarbons.
  • Petroleum is made of a mixture of different hydrocarbons.
  • The most prolific hydrocarbons found in the chemistry of petroleum are alkanes, these are also sometimes known as branched or linear hydrocarbons.

(b) A crystalline form of carbon is Fullerene


  • Fullerenes are pure carbons that are in the shape of a spherical hollow cage like a soccer ball with 60 carbon atoms.
  • It is the only pure form of molecular carbon utilized by our body.
  • ​A fullerene is an allotrope of carbon whose molecule consists of carbon atoms connected by single and double bonds so as to form a closed or partially closed mesh, with fused rings of five to seven atoms.
  • The molecule may be a hollow sphere, ellipsoid, tube, or many other shapes and sizes.
  • The purest form of carbon is fullerenes since they have a smooth structure without dangling bonds.
  • Fullerenes are the pure carbons that are in form of a spherical hollow cage-like soccer ball with 60 carbon atoms. It has twenty, five-membered rings and twelve, six-membered rings. ​

(c) Graphite is not found in Maharashtra

  • The Natural Graphite Mining Companies in Bihar · Sinha Radiance Private Limited · Katyayni & Patel Mining Project Private Limited · Ocean Stone Mines Private Limited.
  • Graphite bodies of economic importance occur in the Eastern Ghats migmatite complex of Orissa, India, which consists of sillimanite-rich gneiss (khondalite), calc-silicate granulite, basic (pyroxene) granulite, and acidic gneiss palaeosomes and a variety of quartzofeldspathic neosomes and pegmatite veins.
  • ​Orissa is the leading producer with 77% & Rajasthan's share is less than 1%.
  • The graphite Deposits of Rajasthan are in Ajmer, Alwar, Banswara, and Jodhpur.
  • Uses. Crucible Industry – electric furnaces.

(d) Diamond is used for cutting and drilling rocks and glass.


  • Carbon has an electronic arrangement of 2,4. In a diamond, each carbon shares electrons with four other carbon atoms by forming four single bonds.
  • It has a very high melting point (almost 4000°C). Very strong carbon-carbon covalent bonds have to be broken throughout the structure before melting occurs.
  • It is very hard. This is again due to the need to break very strong covalent bonds operating in 3-dimensions.
  • Diamonds possess many properties that make them superb for drilling. It takes an incredible amount of durability to cut through tough surfaces, such as concrete, without being damaged. Succeeding in this requires a material that exceeds the toughness of concrete.

(e) Carbon forms innumerable compounds because carbon atoms can form long chains.


  • Catenation is the ability of carbon to form long chains.
  • In fact, carbon atoms are unique because of catenation.
  • carbon chains are formed because they form bonds, or tetravalent bonds, with other carbon atoms.
  • It is due to the bonding of the p-p orbital of carbon atoms to form a long chain. Because carbon has 4 valance electrons. Every electron can bond any hydrogen electron so many new different elements are formed.

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