Tag: chemistry

Questions Related to chemistry

The allotrope of carbon used in nuclear reactor is:

  1. diamond

  2. suger charcoal

  3. graphite

  4. wood charcoal


Correct Option: C
Explanation:

Graphite is the most stable allotrope of carbon.Contrary to popular belief, high-purity graphite does not readily burn, even at elevated temperatures. For this reason,it is used in nuclear reactor and for high-temperature crucibles for melting metals.


 Hence,graphite is used in nuclear reactor and it is a allotrope of carbon.

Graphite is a ______ conductor of electricity whereas diamond is a ______ conductor of electricity.

  1. bad, bad

  2. good, bad

  3. bad, good

  4. good, good


Correct Option: B
Explanation:

Carbon has a valency of 4. In graphite, each carbon atoms 3 electrons are strongly bonded to other carbon atoms forming a hexagonal structure while one of the electrons of graphite is loosely bound and can thus conduct electricity. 


In diamond, each carbon atom is attached to four other carbon atoms forming a tetrahedral structure and has no free or loosely bound electrons. Thus diamond cannot conduct electricity.

Hence, option B is correct.

Some elements show the property of existing in two or more distinct physical form which shows different physical properties but same chemical properties. These distinct forms of an element are called:

  1. isomers

  2. allotropes

  3. compounds

  4. isobars


Correct Option: B
Explanation:

The term allotrope refers to one or more forms of a chemical element that occur in the physical state. Graphite and diamond are both allotropes of carbon that occur in the solid state. Allotropism only refers to different forms of chemical elements.

Due to the weak Van der Waals' forces and less distance between the layers, graphite :

  1. show lubricating property

  2. has lusture

  3. is hexagonal

  4. is a good conductor of electricity


Correct Option: A
Explanation:

Because the layers are only weakly held together they can easily slip over one another, hence, show lubricating property.

(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


Correct Option: D
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.

Carbon can form a maximum of _____ bonds.

  1. 1

  2. 2

  3. 3

  4. 4


Correct Option: D

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)


Correct Option: B
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.

Which one has an allotrophic form that is a good electrical conductor at standard conditions ?

  1. Carbon

  2. Nitrogen

  3. Oxygen

  4. Neon

  5. Argon


Correct Option: A
Explanation:

Carbon has an allotrophic form that is a good electrical conductor at standard conditions.
This allotrope is graphite.

Which of the following element's allotrop is the primary absorber of UV solar radiation in Earth's atmosphere ?

  1. Carbon

  2. Nitrogen

  3. Ozone

  4. Neon

  5. Argon


Correct Option: C
Explanation:

Ozone, an allotrope of oxygen is the primary absorber of UV solar radiation in Earth's atmosphere.


Hence option C is correct.

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


Correct Option: E
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.