This set of Class 12 Chemistry Chapter 1 Multiple Choice Questions & Answers (MCQs) focuses on “Amorphous and Crystalline Solids”.
1. In polar molecular solids, the molecules are held together by ________
a) dipole-dipole interactions
b) dispersion forces
c) hydrogen bonds
d) covalent bonds
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Explanation: Molecular solids are solids that are collections of molecules held together by intermolecular forces. In polar molecules such as HCl, So2, etc., the molecules are held together by dipole-dipole interactions.
2. Diamond is an example of _______
a) solid with hydrogen bonding
b) electrovalent solid
c) covalent solid
d) glass
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Explanation: The solids in which constituent particles are attached to each other by covalent bonds are called covalent solids. Diamond, graphite, silicon, SiC, AIN, quartz are examples of covalent solids.
3. Silicon is found in nature in the forms of ________
a) body-centered cubic structure
b) hexagonal-closed packed structure
c) network solid
d) face-centered cubic structure
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Explanation: Silicon due to its catenation property form network solid. Catenation is the ability of an atom to form bonds with other atoms of the same element. The compounds of silicon are reactive and not stable.
4. Which one of the following are the dimensions of cubic crystal?
a) a =b ≠ c
b) a = b = c and α = β ≠ γ = 90
c) a = b = c and α = β = γ = 90
d) a ≠ b = c and α = β ≠ γ = 90
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Explanation: The dimensions of a cubic crystals are a = b = c, α = β = γ = 90.
5. Which of the following is not a crystal system?
a) Cubic
b) Trigonal
c) Triclinic
d) Hexaclinic
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Explanation: Hexaclinic is not a crystal system. Their crystal system are cubic, tetragonal, rhombohedral or trigonal, orthorhombic or rhombic, monoclinic, triclinic and hexagonal.
6. In face-centred cubic cell, a unit cell is shared equally by __________
a) four unit cells
b) two unit cells
c) one unit cell
d) six unit cells
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Explanation: The unit cell in which atoms are present at corners as well as faces of unit cell is known as face-centred cubic unit cell. In face-centred cubic cell, a unit cell is shared equally by six unit cells.
7. The unit cell with a≠b≠c and α=β=γ=90 refers to __________ crystal system.
a) hexagonal
b) trigonal
c) triclinic
d) orthorhombic
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Explanation: In orthorhombic crystal system, all three axes are unequal in length and all are perpendicular to one another. It is also called as rhombic crystal system. Topaz, barite are some examples of orthorhombic crystals.
8. Which is the most unsymmetrical crystal system?
a) Triclinic crystal system
b) Cubic crystal system
c) Hexagonal crystal system
d) Trigonal crystal system
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Explanation: Most unsymmetrical crystal system is triclinic in which all three axes are unequal in length none is perpendicular to another. Triclinic unit cells has the least symmetrical shape of all unit cells. Turquoise is an example of triclinic crystal.
9. In the simple cubic cell, each corner atom is shared by __________
a) eight unit cells
b) one unit cell
c) two unit cells
d) six unit cells
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Explanation: The unit cell in which the constituent atoms are present only at the corner is known as simple cubic cell. It is also referred to as a primitive cubic cell. In the simple cubic cell, each corner atom is shared by eight different unit cells.
10. The points which shows the position of atoms in crystal are called as _________
a) crystal lattice
b) crystal parameters
c) bravais lattice
d) lattice point
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Explanation: The point at which the atoms may be present on the unit cell is termed as lattice point. It shows the position of atoms in crystal.
11. The unit cell with a≠b≠c and α=γ=90, β≠90 refers to __________crystal system.
a) cubic
b) tetragonal
c) monoclinic
d) triclinic
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Explanation: In monoclinic crystal system, all the three axes are unequal in length and two axes are perpendicular to each other. Gypsum and borax are examples of monoclinic crystals.
12. Which type of solid crystals will conduct heat and electricity?
a) Ionic
b) Covalent
c) Molecular
d) Metallic
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Explanation: Metallic crystals consist of metal cations surrounded by a sea of mobile valence electrons. These electrons are capable of moving through the entire crystal. The metallic crystals conduct heat and electricity due to the presence of these mobile electrons in them.
13. Which is not a characteristic of crystalline solids?
a) They undergo a clean cleavage
b) They are true solids
c) They are isotropic
d) They have sharp melting points
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Explanation: Amorphous solids are isotropic that is they have identical properties in all directions, whereas crystalline solids are anisotropic that is they have different properties in different directions.
14. Which of the following is a characteristic of amorphous solid?
a) They are true solids
b) They have sharp melting points
c) They undergo clear cleavage
d) They are isotropic
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Explanation: Amorphous solids are isotropic that is they have identical properties in all directions. The remaining options are the characteristics of crystalline solids.
15. Solids are classified as ___________
a) crystalline and ionic solids
b) metallic and amorphous solids
c) molecular and covalent solids
d) crystalline and amorphous solids
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Explanation: Based on their crystal structures, solids are classified as crystalline and amorphous solids. In crystalline solids, the constituent particles are arranged in a regular manner. In amorphous solids, the constituent particles are not arranged in any regular manner.
16. Quartz is an example of ___________
a) molecular solids
b) ionic solids
c) covalent solids
d) metallic solids
View Answer
Explanation: Quartz is a common example of covalent solids. In covalent solids, the constituent particles are attached to each other by covalent bonds. Diamond, graphite, silicon are other examples of covalent solids.
17. Solid carbon dioxide is an example of _________
a) metallic crystal
b) covalent crystal
c) ionic crystal
d) molecular crystal
View Answer
Explanation: Solid CO2 is an example of molecular crystal. These solids have molecules as their constituent particles. These solids may be bonded by vander waals’ forces or by dipole-dipole attraction or by strong hydrogen bonds. H2, Cl2, I2 are some examples of molecular solids.
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