ROUTERA

Chapter 1 The Solid State

Class 12th Chemistry Chapter MCQs

1. Which of the following is the correct arrangement of particles in a solid?

a) Randomly arranged
b) Closely packed
c) In a straight line
d) Spread out evenly

Answer: b) Closely packed
Explanation: In solids, particles are closely packed in a regular arrangement, giving them a definite shape and volume.

2. The unit cell that has a sphere at each corner and at the center of the face is called:

a) Simple cubic
b) Body-centered cubic
c) Face-centered cubic
d) Hexagonal

Answer: c) Face-centered cubic
Explanation: In a face-centered cubic (FCC) unit cell, there is an atom at each corner and at the center of each face.

3. The density of a crystal depends on:

a) The mass of the atoms in the crystal
b) The number of atoms in the unit cell
c) The volume of the unit cell
d) All of the above

Answer: d) All of the above
Explanation: The density of a crystal depends on the mass of atoms, the number of atoms in the unit cell, and the volume of the unit cell.

4. In a crystal lattice, the point at the corner of the unit cell represents:

a) A face-center position
b) A body-center position
c) A corner position
d) An edge-center position

Answer: c) A corner position
Explanation: In a crystal lattice, the corner of the unit cell represents a lattice point where atoms or ions are located.

5. Which of the following properties is a characteristic of solids?

a) They are easily compressible
b) They have a definite shape and volume
c) They have a variable shape
d) They have low density

Answer: b) They have a definite shape and volume
Explanation: Solids have a fixed shape and volume due to the strong intermolecular forces between particles.

6. In a simple cubic unit cell, how many atoms are there in one unit cell?

a) 1
b) 2
c) 4
d) 8

Answer: a) 1
Explanation: In a simple cubic unit cell, there is one atom at each corner of the unit cell, and each corner atom is shared by 8 unit cells. Thus, each unit cell contains effectively 1 atom.

7. Which of the following is a characteristic of a crystal system?

a) Symmetry
b) Unit cell shape
c) Lattice point arrangement
d) All of the above

Answer: d) All of the above
Explanation: Crystal systems are classified based on the symmetry of the unit cell, the shape of the unit cell, and the arrangement of lattice points.

8. The coordination number of the atoms in a face-centered cubic (FCC) arrangement is:

a) 4
b) 6
c) 8
d) 12

Answer: d) 12
Explanation: In a face-centered cubic (FCC) arrangement, each atom is surrounded by 12 nearest neighbors, giving it a coordination number of 12.

9. The number of atoms in a body-centered cubic (BCC) unit cell is:

a) 1
b) 2
c) 4
d) 8

Answer: b) 2
Explanation: A body-centered cubic (BCC) unit cell has an atom at the center and at each corner. Each corner atom is shared by 8 unit cells, so the total number of atoms in one unit cell is 2.

10. What type of defect occurs when an atom or ion is missing from its normal lattice position?

a) Schottky defect
b) Frenkel defect
c) Vacancy defect
d) Dislocation defect

Answer: c) Vacancy defect
Explanation: A vacancy defect occurs when an atom or ion is missing from its normal lattice position.

11. Which of the following is true for amorphous solids?

a) They have a well-defined melting point
b) Their particles are arranged in a regular, repeating pattern
c) They exhibit anisotropy
d) They lack a long-range order

Answer: d) They lack a long-range order
Explanation: Amorphous solids do not have a well-defined long-range order in the arrangement of their particles.

12. The term 'crystalline solid' refers to a solid:

a) With no symmetry
b) With a well-defined geometry
c) With random arrangement of particles
d) With irregular shape

Answer: b) With a well-defined geometry
Explanation: Crystalline solids have a regular arrangement of atoms, ions, or molecules that repeat in a regular pattern, forming a well-defined geometry.

13. The type of crystalline solid in which the forces holding the atoms or ions together are purely covalent is called:

a) Molecular solid
b) Ionic solid
c) Metallic solid
d) Covalent network solid

Answer: d) Covalent network solid
Explanation: In covalent network solids, atoms are held together by strong covalent bonds in a continuous network, like in diamond or graphite.

14. In a crystal lattice, the points that represent the positions of the atoms, ions, or molecules are called:

a) Lattice points
b) Interstitial sites
c) Unit cells
d) Edge centers

Answer: a) Lattice points
Explanation: Lattice points in a crystal lattice represent the positions where atoms, ions, or molecules are located.

15. Which of the following is a property of crystalline solids?

a) They have a sharp melting point
b) They are isotropic
c) They exhibit irregular breaking patterns
d) They do not show cleavage

Answer: a) They have a sharp melting point
Explanation: Crystalline solids have a sharp melting point because their particles are arranged in an orderly fashion.

16. The structure of diamond is an example of:

a) Molecular solid
b) Ionic solid
c) Covalent network solid
d) Metallic solid

Answer: c) Covalent network solid
Explanation: Diamond is a covalent network solid where each carbon atom is bonded to four other carbon atoms by strong covalent bonds.

17. The number of atoms in a face-centered cubic (FCC) unit cell is:

a) 1
b) 2
c) 4
d) 8

Answer: c) 4
Explanation: In an FCC unit cell, atoms are located at the corners and at the center of each face, giving a total of 4 atoms per unit cell.

18. The energy required to separate the components of an ionic solid is known as:

a) Heat of fusion
b) Heat of vaporization
c) Lattice energy
d) Ionization energy

Answer: c) Lattice energy
Explanation: Lattice energy is the energy required to break the ionic bonds and separate the ions in an ionic solid.

19. The type of solid in which the constituent particles are ions is:

a) Ionic solid
b) Molecular solid
c) Covalent solid
d) Metallic solid

Answer: a) Ionic solid
Explanation: Ionic solids consist of ions held together by electrostatic forces, such as in sodium chloride (NaCl).

20. Which of the following solids has the highest melting point?

a) Diamond
b) Sodium chloride
c) Water
d) Iron

Answer: a) Diamond
Explanation: Diamond, a covalent network solid, has the highest melting point due to the strong covalent bonds between carbon atoms.

21. In the hexagonal crystal system, the number of axes of different lengths is:

a) 1
b) 2
c) 3
d) 4

Answer: c) 3
Explanation: In the hexagonal crystal system, there are three axes of equal length, and the fourth axis is of a different length.

22. A solid where the constituent particles are held together by van der Waals forces is a:

a) Molecular solid
b) Ionic solid
c) Covalent solid
d) Metallic solid

Answer: a) Molecular solid
Explanation: Molecular solids are held together by weak intermolecular forces such as van der Waals forces.

23. The correct sequence of increasing coordination number is:

a) Simple cubic < Body-centered cubic < Face-centered cubic
b) Face-centered cubic < Body-centered cubic < Simple cubic
c) Simple cubic < Face-centered cubic < Body-centered cubic
d) Body-centered cubic < Simple cubic < Face-centered cubic

Answer: a) Simple cubic < Body-centered cubic < Face-centered cubic
Explanation: The coordination number increases in the order: Simple cubic (6), Body-centered cubic (8), and Face-centered cubic (12).

24. In a molecular solid, the particles at the lattice points are:

a) Atoms
b) Ions
c) Molecules
d) Electrons

Answer: c) Molecules
Explanation: In molecular solids, the lattice points are occupied by molecules held together by weak intermolecular forces.

25. Which of the following is a property of amorphous solids?

a) They have sharp melting points
b) They have a definite structure
c) They show isotropy
d) They are highly ordered

Answer: c) They show isotropy
Explanation: Amorphous solids show isotropy, meaning their properties are the same in all directions due to the lack of long-range order.

26. The type of bond found in graphite is:

a) Ionic bond
b) Covalent bond
c) Metallic bond
d) Hydrogen bond

Answer: b) Covalent bond
Explanation: In graphite, each carbon atom is bonded to three other carbon atoms by covalent bonds, with the fourth electron free to move.

27. Which of the following is NOT a characteristic of a crystal lattice?

a) Regular arrangement of particles
b) Specific geometric shape
c) High electrical conductivity
d) Defined symmetry

Answer: c) High electrical conductivity
Explanation: While crystals exhibit regularity and symmetry, high electrical conductivity is not necessarily a characteristic of all crystal lattices.

28. The phenomenon in which a crystal lattice absorbs energy and rearranges itself is called:

a) Phase transition
b) Lattice distortion
c) Melting
d) Sublimation

Answer: b) Lattice distortion
Explanation: Lattice distortion occurs when a crystal absorbs energy, leading to a rearrangement of its atoms or ions.

29. The number of atoms in a unit cell of sodium chloride (NaCl) is:

a) 1
b) 2
c) 4
d) 8

Answer: b) 2
Explanation: In NaCl, each unit cell contains 4 Na+ ions and 4 Cl− ions, contributing 2 NaCl units.

30. Which of the following is true for a body-centered cubic structure?

a) Each atom is in contact with 12 neighboring atoms
b) The coordination number is 8
c) The atoms are arranged in layers
d) The atoms form a hexagonal shape

Answer: b) The coordination number is 8
Explanation: In a body-centered cubic structure, each atom has 8 nearest neighbors, giving a coordination number of 8.

31. Which type of defect is associated with a misalignment of the lattice structure along a plane?

a) Schottky defect
b) Frenkel defect
c) Dislocation defect
d) Vacancy defect

Answer: c) Dislocation defect
Explanation: Dislocation defects involve misalignment or irregularities in the lattice along a plane.

32. Which of the following is true for ionic solids?

a) They are good conductors of electricity in solid form
b) They have low melting points
c) They are hard and brittle
d) They have high volatility

Answer: c) They are hard and brittle
Explanation: Ionic solids are hard due to strong electrostatic forces between oppositely charged ions but are brittle.

33. The shape of a crystal is determined by:

a) The size of the atoms
b) The shape of the unit cell
c) The intermolecular forces
d) The external temperature

Answer: b) The shape of the unit cell
Explanation: The shape of the crystal is determined by the arrangement of particles in the unit cell and how these units repeat in space.

34. Which of the following types of solids is associated with high electrical conductivity?

a) Molecular solids
b) Covalent solids
c) Ionic solids
d) Metallic solids

Answer: d) Metallic solids
Explanation: Metallic solids have free electrons that allow them to conduct electricity efficiently.

35. The density of a crystalline solid depends on:

a) The size of atoms in the unit cell
b) The packing efficiency
c) The mass of the unit cell
d) All of the above

Answer: d) All of the above
Explanation: The density of a crystalline solid depends on the size of atoms, packing efficiency, and the mass of the unit cell.

36. The force that holds the atoms or ions together in a metallic solid is called:

a) Ionic bond
b) Covalent bond
c) Metallic bond
d) Hydrogen bond

Answer: c) Metallic bond
Explanation: In metallic solids, atoms are held together by metallic bonds, which involve the sharing of free electrons between metal atoms.

37. The defect that causes the ionic solid to be less dense is:

a) Schottky defect
b) Frenkel defect
c) Vacancy defect
d) Dislocation defect

Answer: a) Schottky defect
Explanation: In a Schottky defect, an equal number of cations and anions are missing from their lattice positions, causing the solid to become less dense.

38. The density of a solid can be calculated using:

a) Atomic weight and unit cell volume
b) Lattice energy and atomic radius
c) Bond energy and packing efficiency
d) Atomic number and temperature

Answer: a) Atomic weight and unit cell volume
Explanation: The density of a solid is calculated by dividing the atomic weight by the unit cell volume.

39. Which of the following is characteristic of an ionic solid?

a) High conductivity in solid state
b) Low melting point
c) Strong electrostatic forces between ions
d) Lack of cleavage planes

Answer: c) Strong electrostatic forces between ions
Explanation: Ionic solids are characterized by strong electrostatic forces between oppositely charged ions, resulting in high melting points and brittleness.

40. A crystal lattice defect where a smaller ion occupies an interstitial site is known as:

a) Schottky defect
b) Frenkel defect
c) Vacancy defect
d) Dislocation defect

Answer: b) Frenkel defect
Explanation: A Frenkel defect occurs when an ion is displaced from its normal lattice site and occupies an interstitial site, typically seen with smaller ions.

41. The packing efficiency in a face-centered cubic (FCC) structure is:

a) 52%
b) 68%
c) 74%
d) 100%

Answer: c) 74%
Explanation: The packing efficiency in an FCC structure is 74%, meaning 74% of the available volume is occupied by particles.

42. The coordination number in a simple cubic unit cell is:

a) 4
b) 6
c) 8
d) 12

Answer: b) 6
Explanation: In a simple cubic structure, each atom is surrounded by 6 neighbors, giving it a coordination number of 6.

43. The unit cell of sodium chloride (NaCl) is:

a) Simple cubic
b) Body-centered cubic
c) Face-centered cubic
d) Hexagonal

Answer: c) Face-centered cubic
Explanation: Sodium chloride (NaCl) crystallizes in a face-centered cubic (FCC) unit cell.

44. Which of the following solids can conduct electricity in the solid state?

a) Molecular solids
b) Ionic solids
c) Covalent network solids
d) Metallic solids

Answer: d) Metallic solids
Explanation: Metallic solids can conduct electricity in the solid state due to the presence of free electrons.

45. Which of the following is NOT a crystal system?

a) Cubic
b) Monoclinic
c) Rectangular
d) Rhombohedral

Answer: c) Rectangular
Explanation: The crystal systems are cubic, monoclinic, triclinic, orthorhombic, tetragonal, hexagonal, and rhombohedral. Rectangular is not a crystal system.

46. Which of the following crystal types has no symmetry?

a) Amorphous solids
b) Molecular solids
c) Ionic solids
d) Covalent solids

Answer: a) Amorphous solids
Explanation: Amorphous solids do not exhibit symmetry in the arrangement of their particles.

47. In a crystal lattice, atoms are held together by:

a) Attractive forces only
b) Repulsive forces only
c) Both attractive and repulsive forces
d) None of the above

Answer: c) Both attractive and repulsive forces
Explanation: In a crystal lattice, atoms are held together by both attractive forces (between opposite charges) and repulsive forces (between like charges).

48. The structure of graphite is an example of:

a) Molecular solid
b) Ionic solid
c) Covalent network solid
d) Metallic solid

Answer: c) Covalent network solid
Explanation: In graphite, each carbon atom is covalently bonded to three other carbon atoms in a plane, forming a covalent network.

49. In which type of solids do the constituent particles exist as individual atoms?

a) Molecular solids
b) Ionic solids
c) Covalent network solids
d) Metallic solids

Answer: d) Metallic solids
Explanation: In metallic solids, the constituent particles exist as individual atoms that are surrounded by a "sea" of delocalized electrons.

50. Which of the following properties is observed in both crystalline and amorphous solids?

a) Definite shape
b) High density
c) Brittleness
d) Both show isotropy

Answer: c) Brittleness
Explanation: Both crystalline and amorphous solids can exhibit brittleness, although their structures differ. Crystalline solids are brittle due to their rigid lattice structure, while amorphous solids are brittle due to their lack of long-range order.