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Multiple choice chemistry occurrence of carbon compounds in nature organic compounds allotropes of carbon versatile nature of carbon

Which of the following is not an allotropic form of carbon?

  1. Fluorine

  2. Fullerene

  3. Diamond

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

Fullerene, graphite and diamond all are different allotrops of carbon.

Fluorine is an entirely different element, whose atomic number is $9$.
Option A is the correct answer.
Fluorine is not an allotrope of carbon.

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

Which of the following is the true statement for carbon atoms :

  1. A carbon atom loses $4$ electrons.
  2. A carbon atom forms $4$ covalent bonds.
  3. A carbon atom share the $2$ electrons in the first principal energy level.
  4. A carbon atom gains $4$ electrons.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carbon atoms form 4 covalent bonds. Carbon (atomic number 6) has electronic configuration $\displaystyle 1s^2 2s^22p^4$ It has $4$ valence electrons which are shared with other atoms to form $4$ covalent bonds.

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

____________ is the crystalline allotrope of carbon.

  1. Coal

  2. Coke

  3. Diamond

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

Graphite is one of three forms of crystalline, or crystal-forming, carbon. Carbon also exists in an amorphous, or “shapeless,” form in substances such as coal and coke. Different forms of the same element are called allotropes. Besides graphite, the other allotropes of crystalline carbon are diamond and fullerenes


Hence, the correct options are $C$ and $D$

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

Which of the following elements shows allotropy ?

  1. Mg

  2. Cs

  3. Sn

  4. Zn
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Allotropy is a phenomenon wherein an element especially from group $13$ to group $16$ exists in more than one form. These forms differ in arrangement of atoms in their crystalline form. Few list of various elements showing allotropy -

 

Forms | | --- | --- | | Carbon : | Graphite, Diamond, Fullerenes | | Sulphur $(S _{8})$: | Rhombic, Monocline, Triclinic sulphur | | Phosphorous $(P _{4})$:  | Red, Black, Yellow | | Tin $(Sn)$: | White, Grey |

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

Diamond and graphite are the covalent compounds of carbon element (C).

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The giant molecular structure of carbon is lattices made up of carbon which are covalently bonded. These bonds are very strong due to which they are hard and have high melting points. 

Diamond is an allotrope of carbon in which the carbon atoms are arranged in cubic lattice or diamond lattice. In diamond, each carbon atom has four neighbors joined to it with covalent bonds. 

In graphite, the carbon atoms are arranged hexagonally in a planar condensed ring system. The layers are stacked parallel to each other.  The atoms within the rings are bonded covalently, whilst the layers are loosely bonded together by van der Waals forces. 

Therefore, Diamond and graphite are the covalent compounds of carbon element (C).
Multiple choice chemistry the world of carbon organic compounds allotropes of carbon versatile nature of carbon

$C _{graphite}+O _{2(g)}\rightarrow CO _{2(g)}; \Delta H=-393.5kJ, \Delta H$ of the reaction cannot be:

  1. Heat of formation of $CO _{2}$
  2. Heat of combustion of $CO _{2}$

  3. Heat of reaction

  4. Heat of transition
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$C(graphite)+O _2(g)\longrightarrow CO _2(g)$


Now, here $\Delta H$ of the reaction cannot be the heat of transition, because there is no transition between phase take place at constant temperature and pressure.

For example: transition of $C _{diamond}\to C _{graphite}$

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

Which of the following statements are incorrect?


I.  Diamond is the hardest natural substance known and has very high melting and boiling point. 

II. Iodine is a metal like lithium, sodium, and potassium are so hard that they cannot be cut with a knife. They have high densities and high melting point. 

III. Graphite is a metal.


IV. Most of the non- metals produce acidic oxides while most of the metals produce basic oxides.

V. Graphite is a conductor of electricity.

  1. I, IV and V only

  2. I, III, IV and V only

  3. II and III only

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Statement II is incorrect because iodine is a non-metal and alkali metals (Li, Na, K) are soft enough to be cut with a knife. Statement III is incorrect because graphite is a non-metal (allotrope of carbon).