Tag: the world of carbon

Questions Related to the world of carbon

Diamond is not a good conductor of electricity because :

chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

  1. it is very hard

  2. it is structure is very compact

  3. it is not water soluble

  4. it has no free electrons to conduct electric current

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Correct Option: D

Which is/are the characteristic(s) of Diamond?

chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

  1. Opaque

  2. Hardness

  3. Both $A$ and $B$

  4. Conductor of electricity

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Correct Option: B
Explanation:

Diamond is transparent, hard and poor conductor of electricity. In-fact, diamond is hardest known substance on earth. The hardness is due to the presence of strong covalent bonds between C atoms. Hence, the option (B) is the correct answer.

Two adjacent layers in graphite are bonded by comparatively _______ forces.

chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

  1. strong

  2. weak

  3. both A and B

  4. none of these

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Correct Option: B
Explanation:

Graphite is an allotrope of carbon. Each carbon is covalently bobded to other three carbon atoms, it contains layers of carbon. The layers slid over each other easily because of the weak Van der Walls' forces between them.

Crystalline fullerene has __________ properties.

chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

  1. semiconducting

  2. insulating

  3. both $A$ and $B$

  4. none of these

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Correct Option: A
Explanation:

Fullerene is an allotrope of carbon in the form of hollow sphere and called as buckyballs. $C-60$ is the crystalline form and is used as semiconductor.

Density of graphite is :

chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

  1. $0.5\ g/cm^3$

  2. $2.266\ g/cm^3$

  3. $1.08\ g/cm^3$

  4. none of the above

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Correct Option: B
Explanation:

Crystal density of graphite is $2.266 g/cm^3$ as compared with $3.53 g/cm^3$ for diamond.
In the graphite structure, only three of the four valence electrons of carbon form regular covalent bonds with adjacent carbon atoms.

The most stable fullerene is :

chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

  1. $C _{60}$

  2. $C _{70}$

  3. $C _{100}$

  4. $C _{90}$

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Correct Option: A
Explanation:

C-60 is the most stable form and it led the scientists to the conclusion that the cluster must be a spheroidal closed cage in the form of icosahedron.

The first fullerene was discovered in :

chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

  1. $1970$

  2. $1967$

  3. $1997$

  4. $1985$

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Correct Option: D
Explanation:

The first fullerene was discovered in 1985 by Sir Harold W.Kroto, Smalley and Robert F.Curl. They obtained a cage like molecules composed of 60 carbon atoms.

The most common fullerene is $C {60}$. 60 C-atoms are arranged in _____ pentagons and ______ hexagons.

chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

  1. $12, 20$

  2. $16, 26$

  3. $12, 40$

  4. $16, 40$

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Correct Option: A
Explanation:

60 carbon atoms are joined together by single and double bonds to form a hollow sphere with 12 pentagonal and 20 hexagonal faces, a design that resembles a football.

Chemically, diamond is :

chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

  1. a mixture of metal carbonates

  2. pure carbon

  3. a pure form of sand

  4. a mixture of calcium and magnesium phosphates

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Correct Option: B
Explanation:

Diamond is an allotrope of carbon and it is present in pure form since it contains carbon atoms tetrahedrally bonded to each other.

Which of the following statement is true for graphite?


(a) In graphite, each carbon atom is bonded to four other carbon atoms.
(b) Graphite is very hard.
(c) It is a good conductor of electricity.
(d) It is bad conductor of electricity.

chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

  1. a, b and d

  2. only c

  3. a and d

  4. a and c

Show answer
Correct Option: B
Explanation:

The  statement C is  true for graphite.
(a) In graphite, each carbon atom is bonded to three other carbon atoms.
(b) Graphite is soft.
(c) It is a good conductor of electricity as delocalised electrons are free to move in delocalised molecular orbitals.