Case Study Question 03


Chapter 4: Carbon and its Compounds

Class 10

Read the following passage carefully and answer the following questions:
The phenomenon of the existence of an element in two or more physical forms within the same physical state is known as allotropy. Allotropes have similar chemical properties but they differ in chemical properties. In crystalline form, Carbon occurs as graphite, diamond, and fullerenes. Diamond is the hardest natural substance known and is used in cutting marbles, granite, and glass. Graphite is a greyish black and opaque substance, lighter than a diamond with comparative low density. Graphite has a sheet-like structure having hexagonal layers. One layer slides over the other layer due to weak forces and hence it is soft to touch and breaks easily. Graphite is also used as a lubricant.

Substance A is a moderate conductor of electricity. Observe the structure of substance A given below.

Statement I – It is a covalent compound.
Statement II – It has a giant molecular structure.
Statement III – It has the same structure as graphite.
Statement IV – It has the same structure as diamond.

(a) I and III
(b) II and III
(c) II and IV
(d) I, II and IV

(c) II and IV

Which of the following is correct about the structure of diamond?

(a) Carbon atoms are held together by single covalent bonds.
(b) Electrons move freely through the structure.
(c) Layers of atoms slide easily over each other.
(d) Carbon atoms conduct electricity in the molten state.

(a) Carbon atoms are held together by single covalent bonds

Which three allotropes of carbon do the given figures represent?Case Study 01

(a) I-Graphite II-Diamond III-Fullerene
(b) I-Diamond II-Fullerene III-Graphite
(c) I-Graphite II-Fullerene III-Diamond
(d) I-Fullerene II-Graphite III-Diamond

(a) I-Graphite II-Diamond III-Fullerene

Identify the incorrect statement(s):

I. Diamond is the hardest substance known while graphite breaks easily.
II. Each carbon atom in diamond is bonded to 4 other carbon atoms in a tetrahedral manner to form a giant lattice. All carbon atoms are bonded by strong covalent bonds.
III. Graphite is poor conductor of electricity unlike other non metals.
IV. In each layer of graphite, each carbon atom is bonded to three other carbon atoms foming hexagonal rings of carbon atoms.

(a) I and III
(b) Only III
(c) II and IV
(d) I, II and IV

(b) Only III 

The number of carbon atoms surrounding each carbon atom in a diamond are:

(a) 3
(b) 4
(c) 2
(d) 5

(b) 4 

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