Tag: the world of carbon

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Questions Related to the world of carbon

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

(i) It is used in making leads of pencils.
(ii) It is used as dry lubricant.
(iii) It is used in making black paint and printers ink.
(iv) It is used in nuclear reactors as moderator.


Which is this substance?

  1. Diamond

  2. Buckminister fullerene

  3. Lampblack

  4. Graphite
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The substance with the following applications is graphite. It is an allotrope of carbon.
(i) It is used in making leads of pencils.
(ii) It is used as a dry lubricant.
(iii) It is used in making black paint and printers ink.
(iv) It is used in nuclear reactors as a moderator.

Graphite is also used in making electrodes and carbon arcs and in the refractory crucible.

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

Which of the following can conduct electricity in the solid state ?

  1. Sucrose, $C _{12}H _{22}O _{11}$(s)

  2. Graphite, C(s)

  3. Sodium hydroxide, NaOH(s)
  4. Iron(III) chloride, $FeCl^3$(s)
  5. Iodine, $I _2$(s)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Graphite, C(s) can conduct electricity in the solid state.
Ferric chloride and sodium hydroxide are ionic solids which do not conduct electricity in solid state.
They conduct electricity in molten state or in aqueous solution.
Iodine and sucrose are molecular solids which do not conduct electricity.
Graphite is a network solid and conducts electricity as it has delocalised molecular orbitals in which delocalised electrons are free to move.

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

In which of the given pairs the two compounds are allotropes of the same element?

  1. $Br _{2}$ and $Hg$
  2. $Cl _{2}$ and $F _{2}$
  3. $NH _{4}^{+}$ and $H _{3}O^{+}$
  4. $Fe$ and $CO$

  5. Diamond and graphite
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Diamond and graphite are allotropes of each other.
They are are allotropes of carbon. Allotropes are different forms of same element. Another allotrope of carbon is fullerene.

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

The number of free electrons in the outermost shell of carbon in graphite is:

  1. four

  2. one

  3. two

  4. three
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The number of free electrons in the outermost shell of carbon in graphite is one. Each $\displaystyle C$ atom is $\displaystyle sp^2$ hybridised. Each $\displaystyle C$ atom forms 3 covalent bonds with 3 other $\displaystyle C$ atoms. Thus, each $\displaystyle C$ atom has one electron in unhybridized $\displaystyle 2p$ orbital which it uses for $\displaystyle \pi $ bonding.

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

Select the correct statement.

  1. Carbon-carbon bond order in graphite is more than diamond

  2. Carbon-carbon bond order in graphite is less than diamond
  3. Hybridization of each carbon in diamond is ${sp}^{2}$
  4. Hybridization of each carbon in graphite is ${sp}^{3}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hybridization of carbon is $sp^2$ in graphite as $1$ carbon atom is joined to $3$ other carbon atoms. In diamond, the hybridization is $sp^3$ as $1$ carbon atom is joined to $4$ other carbon atoms.

Bond order= $\cfrac {\text {Total number of valence electrons of carbon}}{\text {number of }\sigma\text { bonds}}$
For graphite, $B.O= \cfrac {4}{3}= 1.33$,
For diamond, $B.O= \cfrac {4}{4}=1$ .
Hence, Bond order for graphite is more than that for diamond.

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

Which of the following statements is/are correct?


(1) Graphite is used in making electrodes because it can conduct electricity.
(2) Graphite is used as a solid lubricant.
(3) Graphite is used in the manufacture of crucibles.
(4) Graphite is also known as black lead.

  1. 1 and 4

  2. 2 and 3

  3. 1 and 2

  4. All of them
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

All statements are correct: graphite conducts electricity due to delocalized electrons, acts as a lubricant due to its layered structure, is used in crucibles due to its high melting point, and is historically called black lead.