C H A P T E R
01
The Solid State
A Quick Recapitulation of the Chapter
1. Solids have definite mass, volume and shape due to the fixed positions of their constituent particles.
2. They may be crystalline (i.e having long range order of constituents) or amorphous (i.e having short range order of
constituents).
3. Crystal lattice is the three dimensional arrangement of constituents or points in a crystalline solid. The smallest
repeating unit of the crystal lattice is called the unit cell.
There are seven primitive unit cells whose possible variations as centred unit cells are listed below.
Systems Parameters Interaxial angles Examples
Triclinic a ≠b ≠c α ≠ β ≠ γ ≠ 90° K 2 Cr2 O 7,CuSO 4 ⋅ 5H 2 O,H 3 BO 3
Monoclinic a ≠b ≠c α = γ = 90° ≠ β Na 2SO 4 ⋅10H2O,Na 2 B4O 7 ⋅ 10 H 2O, Monoclinic sulphur
Orthorhombic a ≠b ≠c α = β = γ = 90° KNO 3 ,K 2SO 4 ,BaSO 4 ,PbCO 3 , Rhombic sulphur
Tetragonal a =b ≠c α = β = γ = 90° White tin, SnO 2 , TiO 2 ,NiSO 4
Cubic a =b =c α = β = γ = 90° NaCl,KCl,CsCl, ZnS,CaF2 , Diamond
Hexagonal a =b ≠c α = β = 90°, γ =120 ° ZnO,CdS,HgS, Graphite
Rhombohedral (Trigonal) a = b = c α = β = γ ≠ 90° NaNO 3 ,ICI, Calcite, Quartz
4. Types of Cubic Unit Cell
(i) In Simple-Cubic Unit Cell (sc) all the eight corners of the cube are occupied by atoms, ions or molecules.
(ii) In Body-Centred Cubic Unit Cell (bcc) the constituent particles occupy all the eight corners of the cube and one
particle is located at the body centre of the cube.
(iii) In Face-Centred Cubic Unit Cell (fcc) the constituent particles occupy all the eight corners of the cube and also the
centre of the six faces of the cube.
5. In hcp structure order is ABABAB...
6. In ccp, it is ABCABC...
7. Unit cell parameters
Type/feature sc bcc fcc
Number of atom per unit cell, Z 1 2 4
Radius of atom, r a/2 3a /4 a /2 2
Packing fraction (total occupied space) 52.4% 68% 74%
CN — 8 12
, a 13. F-centres (or Farbenzenter) are electron filled
8. Ionic radius for fcc structure, ra + rc =
2 vacancy of anion, generated due to metal excess
3a defect.
for bcc structure, rc + ra =
2 14. Semiconductors have conductivity in between
where, rc and ra = radius of cation and anion respectively.
conductors and insulators and are of two types:
Z ×M
9. Density of unit cell, d = 3 (i) p-type (group 13 element is added into element of
a × NA
group 14).
where, Z = number of atoms per unit cell (ii) n-type (group 15 element is added into element of
M = atomic or molecular mass group 14).
N A = Avogadro’s number 15. Paramagnetic substances show magnetic
a 3 = volume and a = edge length behaviour only under the influence of the applied
10. If number of atoms = N, magnetic field.
then, number of tetrahedral voids = 2 × N 16. Ferromagnetic substances exhibit magnetism even
and number of octahedral voids = N when applied magnetic field is removed.
11. Schottky defect (a stoichiometric point defect) is due 17. Antiferromagnetic substances have no magnetic
to missing of equal number of atoms from their sites moment since the electronic spins mutually
and hence, results in decrease in density. It is found in cancel under the influence of external magnetic
NaCl, KCl, AgBr etc . field.
12. Frenkel defect (a stoichiometric defect) is due to 18. Ferrimagnetic substances exhibit some magnetic
occupation of an interstitial site by an atom leaving its character due to alignment of the electron spins in
original site vacant. Hence, density remains the same parallel and antiparallel directions in unequal
throughout, e.g. AgBr, AgCl etc. numbers.
Objective Questions Based on NCERT Text
Topic 1
Introduction and Classification of Solids
1. Select the correct statement. 4. What is the necessary condition for the existence of
(a) Matter can exist only in solid, liquid and gaseous states solids?
(b) At low temperature, intermolecular forces are strong (a) Intermolecular forces should be weaker than thermal
enough to keep the constituents together energy
(c) Combined effect of intermolecular forces and (b) Intermolecular forces should be stronger than thermal
intermolecular strength decides the phase of a substance energy
(d) All of the given statements are correct (c) Intermolecular forces should be equal to the thermal
energy
2. Which of the following statement is incorrect? (d) No definite relationship between them
(a) Solids have different types of structure
(b) Solids have different arrangements of particles 5. Which of the following statement(s) is not true
(c) Properties of solids are independent of nature of its about the properties of solids?
particles (a) They are compressible and rigid
(d) Solids like biodegradable polymers are fit for packaging (b) Intermolecular distances are short
purposes (c) Intermolecular forces are strong
(d) They have definite shape, volume and mass
3. Which of the following properties tends to keep
the solid particles apart by making them to move 6. High density and low compressibility are
faster? responsible for which type of solid molecules?
(a) Low temperature (b) Intermolecular forces (a) Highly packed solid (b) Low packed solid
(c) Thermal energy (d) Both (b) and (c) (c) Flexible solid (d) None of these
, 7. The incorrect statement among the following is 15. Solid SO2 and NH3 are the examples of which of the
(a) order of arrangement is the basic aspect to classify following types of solids?
solids into amorphous or crystalline (a) Polar molecular solids
(b) each constituent of a crystalline solid has a definite (b) Non-polar molecular solids
geometrical shape (c) Hydrogen bonded molecular solids
(c) in crystalline as well as amorphous solid periodically (d) None of the above
repeating pattern of constituent can be observed
16. Which of the following can be regarded as molecular
(d) None of the above
solid?
8. Quartz is crystalline silica but silica glass is (a) AlN (b) SiC (c) I2 (d) Diamond
(a) amorphous (b) crystalline
17. Which one of the following forms a molecular solid
(c) Both (a) and (b) (d) None of these
when solidified?
9. Which of the following statement(s) is/are true (a) Silicon carbide (b) Calcium fluoride
regarding crystalline solids? (c) Rock salt (d) Methane
(a) These possess long range order
18. Which of the following is not the characteristic of
(b) These have sharp melting point
(c) These are anisotropic
ionic solids?
(d) All of the above (a) Brittle nature
(b) Very low value of electrical conductivity in the molten
10. Which of the following statements about amorphous state
solids is incorrect? (c) Anisotropic nature
(a) They melt over a range of temperature (d) Very strong forces of attraction
(b) They are isotropic
19. Select the incorrect option regarding metallic solids.
(c) They are rigid and incompressible
(a) Positive ions are surrounded by a sea of free electrons
(d) There is no orderly arrangement of particles
(b) These electrons are mobile
11. Select the correct statement. (c) Covalent bonds are strong and directional
(a) Melting point of quartz glass is sharp but of quartz is not (d) These are highly malleable and ductile
(b) Salt has long range order of constituents but ice does not 20. The luster of a metal is due to
(c) Heat of fusion is definite for iron but not for rubber (a) its high polishing (b) its high density
(d) Glass can give two pieces with plain and smooth (c) chemical inertness (d) presence of free electrons
surfaces when cut with a sharp edged tool
21. The lattice points of a crystal of hydrogen iodide are
12. Some of the physical properties of crystalline solids occupied by
like refractive index show different values on (a) HI molecules
measuring along different directions in the same (b) H atoms and I atoms
crystals. This property is called (c) H + cations and I − anions
(a) isotropy (d) H2 molecules and I2 molecules
(b) cleavage property
22. The false statement about giant molecules is
(c) anisotropy
(a) these are very hard and brittle
(d) None of the above
(b) they may decompose before melting
13. When cut with a sharp edged tool, crystalline (c) they are conductor of electricity
solids split into two pieces and the newly generated (d) graphite is an example of such molecules
surfaces are plain and smooth. This property is 23. Which of the following does not show electrical
known as conduction in its physical states?
(a) anisotropy (b) isotropy
(a) Sodium (b) Diamond (c) Graphite (d) Calcium
(c) cleavage property (b) None of these
24. A solid X is very hard and has a very high melting
14. Hydrogen, chlorine belong to a class of crystalline point. In solid state it is non-conductor but in molten
solids. The true statement related to this class is state, it conducts electricity. Identify X .
(a) the constituents are either atoms or molecules having (a) Molecular (b) Ionic (c) Covalent (d) Metallic
polar dispersion forces
(b) they have low melting point and are hard 25. Which of the following exists as covalent crystals in
(c) they can exist only in gaseous state at room the solid state? (JEE Main 2013)
temperature and pressure (a) Iodine (b) Silicon
(d) the intermolecular forces are weak dispersion or (c) Sulphur (d) Phosphorus
London forces
, Topic 2
Crystal Lattices and Unit Cells
26. Select the incorrect statement. 34. Which of the following figure shows space filling
(a) Crystal lattice is the regular three dimensional structure model of unit cell?
arrangement of constituents in space
(b) There are 7 crystal systems and 14 Bravais lattices
(c) Unit cell is the smallest repeating unit of the crystal
lattice (a) (b)
(d) A unit cell is characterised by two parameters a bond
angle and a bond length
27. Smallest portion of a crystal lattice which on
repetition in different directions generates the entire
lattice is called
(c) (d)
(a) unit cell (b) crystal lattice
(c) lattice point (d) lattice site
28. When constituent particles are present only on the
corner positions of a unit cell, it is called
(a) primitive unit cell (b) centred unit cell
(c) body-centred unit cell (d) face-centred unit cell 35.
29. Which of the following crystal system has cinnabar as
an example?
Fig. (i) Fig. (ii) Fig. (iii)
(a) Cubic (b) Monoclinic
(c) Trigonal (d) Triclinic Which of the above figure shows only primitive cubic
30. Identify the type of crystal system of the following structure of unit cell?
( A ) KNO 3 ; ( B ) CaCO 3 ; (C ) CaSO 4 ; (a) Both (i) and (ii) (b) Both (i) and (iii)
(c) Both (ii) and (iii) (d) All of these
( D ) CuSO 4 ⋅ 5H 2O
(a) A-Cubic; B-Triclinic; C-Hexagonal; D-Rhombohedral 36.
(b) A-Tetragonal; B-Monoclinic; C-Triclinic; D-Hexagonal
(c) A-Orthorhombic; B-Trigonal; C-Tetragonal; D-Triclinic
(d) A-Rhombohedral; B-Hexagonal; C-Trigonal;
D-Orthorhombic
31. The axial angles in triclinic crystal system are
(a) α = β = γ = 90° (b) α = γ = 90° ,β ≠ 90°
(c) α ≠ β ≠ γ ≠ 90° (d) α = β = γ ≠ 90°
32. Which crystal system has no rotation of symmetry?
(a) Hexagonal (b) Orthorhombic In the above figure, structure of unit cell represent
(c) Cubic (d) Triclinic that each corner atom is shared between
(a) 8 unit cell (b) 6 unit cell
33. In which of the following structure unit cell shows the
(c) 4 unit cell (d) 2 unit cell
triclinic structure?
37. How much part of any corner constituent particle
γ c
actually belongs to a particular unit cell?
1 1
(a) α (b) (a) th (b) th
4 6
b 1 1
β (c) th (d) th
a 8 10
38. Contribution of each atom per unit cell at face centre
(c) (d) in a fcc unit cell is
(a) 1 (b) 2
(c) 0.5 (d) 2.5
01
The Solid State
A Quick Recapitulation of the Chapter
1. Solids have definite mass, volume and shape due to the fixed positions of their constituent particles.
2. They may be crystalline (i.e having long range order of constituents) or amorphous (i.e having short range order of
constituents).
3. Crystal lattice is the three dimensional arrangement of constituents or points in a crystalline solid. The smallest
repeating unit of the crystal lattice is called the unit cell.
There are seven primitive unit cells whose possible variations as centred unit cells are listed below.
Systems Parameters Interaxial angles Examples
Triclinic a ≠b ≠c α ≠ β ≠ γ ≠ 90° K 2 Cr2 O 7,CuSO 4 ⋅ 5H 2 O,H 3 BO 3
Monoclinic a ≠b ≠c α = γ = 90° ≠ β Na 2SO 4 ⋅10H2O,Na 2 B4O 7 ⋅ 10 H 2O, Monoclinic sulphur
Orthorhombic a ≠b ≠c α = β = γ = 90° KNO 3 ,K 2SO 4 ,BaSO 4 ,PbCO 3 , Rhombic sulphur
Tetragonal a =b ≠c α = β = γ = 90° White tin, SnO 2 , TiO 2 ,NiSO 4
Cubic a =b =c α = β = γ = 90° NaCl,KCl,CsCl, ZnS,CaF2 , Diamond
Hexagonal a =b ≠c α = β = 90°, γ =120 ° ZnO,CdS,HgS, Graphite
Rhombohedral (Trigonal) a = b = c α = β = γ ≠ 90° NaNO 3 ,ICI, Calcite, Quartz
4. Types of Cubic Unit Cell
(i) In Simple-Cubic Unit Cell (sc) all the eight corners of the cube are occupied by atoms, ions or molecules.
(ii) In Body-Centred Cubic Unit Cell (bcc) the constituent particles occupy all the eight corners of the cube and one
particle is located at the body centre of the cube.
(iii) In Face-Centred Cubic Unit Cell (fcc) the constituent particles occupy all the eight corners of the cube and also the
centre of the six faces of the cube.
5. In hcp structure order is ABABAB...
6. In ccp, it is ABCABC...
7. Unit cell parameters
Type/feature sc bcc fcc
Number of atom per unit cell, Z 1 2 4
Radius of atom, r a/2 3a /4 a /2 2
Packing fraction (total occupied space) 52.4% 68% 74%
CN — 8 12
, a 13. F-centres (or Farbenzenter) are electron filled
8. Ionic radius for fcc structure, ra + rc =
2 vacancy of anion, generated due to metal excess
3a defect.
for bcc structure, rc + ra =
2 14. Semiconductors have conductivity in between
where, rc and ra = radius of cation and anion respectively.
conductors and insulators and are of two types:
Z ×M
9. Density of unit cell, d = 3 (i) p-type (group 13 element is added into element of
a × NA
group 14).
where, Z = number of atoms per unit cell (ii) n-type (group 15 element is added into element of
M = atomic or molecular mass group 14).
N A = Avogadro’s number 15. Paramagnetic substances show magnetic
a 3 = volume and a = edge length behaviour only under the influence of the applied
10. If number of atoms = N, magnetic field.
then, number of tetrahedral voids = 2 × N 16. Ferromagnetic substances exhibit magnetism even
and number of octahedral voids = N when applied magnetic field is removed.
11. Schottky defect (a stoichiometric point defect) is due 17. Antiferromagnetic substances have no magnetic
to missing of equal number of atoms from their sites moment since the electronic spins mutually
and hence, results in decrease in density. It is found in cancel under the influence of external magnetic
NaCl, KCl, AgBr etc . field.
12. Frenkel defect (a stoichiometric defect) is due to 18. Ferrimagnetic substances exhibit some magnetic
occupation of an interstitial site by an atom leaving its character due to alignment of the electron spins in
original site vacant. Hence, density remains the same parallel and antiparallel directions in unequal
throughout, e.g. AgBr, AgCl etc. numbers.
Objective Questions Based on NCERT Text
Topic 1
Introduction and Classification of Solids
1. Select the correct statement. 4. What is the necessary condition for the existence of
(a) Matter can exist only in solid, liquid and gaseous states solids?
(b) At low temperature, intermolecular forces are strong (a) Intermolecular forces should be weaker than thermal
enough to keep the constituents together energy
(c) Combined effect of intermolecular forces and (b) Intermolecular forces should be stronger than thermal
intermolecular strength decides the phase of a substance energy
(d) All of the given statements are correct (c) Intermolecular forces should be equal to the thermal
energy
2. Which of the following statement is incorrect? (d) No definite relationship between them
(a) Solids have different types of structure
(b) Solids have different arrangements of particles 5. Which of the following statement(s) is not true
(c) Properties of solids are independent of nature of its about the properties of solids?
particles (a) They are compressible and rigid
(d) Solids like biodegradable polymers are fit for packaging (b) Intermolecular distances are short
purposes (c) Intermolecular forces are strong
(d) They have definite shape, volume and mass
3. Which of the following properties tends to keep
the solid particles apart by making them to move 6. High density and low compressibility are
faster? responsible for which type of solid molecules?
(a) Low temperature (b) Intermolecular forces (a) Highly packed solid (b) Low packed solid
(c) Thermal energy (d) Both (b) and (c) (c) Flexible solid (d) None of these
, 7. The incorrect statement among the following is 15. Solid SO2 and NH3 are the examples of which of the
(a) order of arrangement is the basic aspect to classify following types of solids?
solids into amorphous or crystalline (a) Polar molecular solids
(b) each constituent of a crystalline solid has a definite (b) Non-polar molecular solids
geometrical shape (c) Hydrogen bonded molecular solids
(c) in crystalline as well as amorphous solid periodically (d) None of the above
repeating pattern of constituent can be observed
16. Which of the following can be regarded as molecular
(d) None of the above
solid?
8. Quartz is crystalline silica but silica glass is (a) AlN (b) SiC (c) I2 (d) Diamond
(a) amorphous (b) crystalline
17. Which one of the following forms a molecular solid
(c) Both (a) and (b) (d) None of these
when solidified?
9. Which of the following statement(s) is/are true (a) Silicon carbide (b) Calcium fluoride
regarding crystalline solids? (c) Rock salt (d) Methane
(a) These possess long range order
18. Which of the following is not the characteristic of
(b) These have sharp melting point
(c) These are anisotropic
ionic solids?
(d) All of the above (a) Brittle nature
(b) Very low value of electrical conductivity in the molten
10. Which of the following statements about amorphous state
solids is incorrect? (c) Anisotropic nature
(a) They melt over a range of temperature (d) Very strong forces of attraction
(b) They are isotropic
19. Select the incorrect option regarding metallic solids.
(c) They are rigid and incompressible
(a) Positive ions are surrounded by a sea of free electrons
(d) There is no orderly arrangement of particles
(b) These electrons are mobile
11. Select the correct statement. (c) Covalent bonds are strong and directional
(a) Melting point of quartz glass is sharp but of quartz is not (d) These are highly malleable and ductile
(b) Salt has long range order of constituents but ice does not 20. The luster of a metal is due to
(c) Heat of fusion is definite for iron but not for rubber (a) its high polishing (b) its high density
(d) Glass can give two pieces with plain and smooth (c) chemical inertness (d) presence of free electrons
surfaces when cut with a sharp edged tool
21. The lattice points of a crystal of hydrogen iodide are
12. Some of the physical properties of crystalline solids occupied by
like refractive index show different values on (a) HI molecules
measuring along different directions in the same (b) H atoms and I atoms
crystals. This property is called (c) H + cations and I − anions
(a) isotropy (d) H2 molecules and I2 molecules
(b) cleavage property
22. The false statement about giant molecules is
(c) anisotropy
(a) these are very hard and brittle
(d) None of the above
(b) they may decompose before melting
13. When cut with a sharp edged tool, crystalline (c) they are conductor of electricity
solids split into two pieces and the newly generated (d) graphite is an example of such molecules
surfaces are plain and smooth. This property is 23. Which of the following does not show electrical
known as conduction in its physical states?
(a) anisotropy (b) isotropy
(a) Sodium (b) Diamond (c) Graphite (d) Calcium
(c) cleavage property (b) None of these
24. A solid X is very hard and has a very high melting
14. Hydrogen, chlorine belong to a class of crystalline point. In solid state it is non-conductor but in molten
solids. The true statement related to this class is state, it conducts electricity. Identify X .
(a) the constituents are either atoms or molecules having (a) Molecular (b) Ionic (c) Covalent (d) Metallic
polar dispersion forces
(b) they have low melting point and are hard 25. Which of the following exists as covalent crystals in
(c) they can exist only in gaseous state at room the solid state? (JEE Main 2013)
temperature and pressure (a) Iodine (b) Silicon
(d) the intermolecular forces are weak dispersion or (c) Sulphur (d) Phosphorus
London forces
, Topic 2
Crystal Lattices and Unit Cells
26. Select the incorrect statement. 34. Which of the following figure shows space filling
(a) Crystal lattice is the regular three dimensional structure model of unit cell?
arrangement of constituents in space
(b) There are 7 crystal systems and 14 Bravais lattices
(c) Unit cell is the smallest repeating unit of the crystal
lattice (a) (b)
(d) A unit cell is characterised by two parameters a bond
angle and a bond length
27. Smallest portion of a crystal lattice which on
repetition in different directions generates the entire
lattice is called
(c) (d)
(a) unit cell (b) crystal lattice
(c) lattice point (d) lattice site
28. When constituent particles are present only on the
corner positions of a unit cell, it is called
(a) primitive unit cell (b) centred unit cell
(c) body-centred unit cell (d) face-centred unit cell 35.
29. Which of the following crystal system has cinnabar as
an example?
Fig. (i) Fig. (ii) Fig. (iii)
(a) Cubic (b) Monoclinic
(c) Trigonal (d) Triclinic Which of the above figure shows only primitive cubic
30. Identify the type of crystal system of the following structure of unit cell?
( A ) KNO 3 ; ( B ) CaCO 3 ; (C ) CaSO 4 ; (a) Both (i) and (ii) (b) Both (i) and (iii)
(c) Both (ii) and (iii) (d) All of these
( D ) CuSO 4 ⋅ 5H 2O
(a) A-Cubic; B-Triclinic; C-Hexagonal; D-Rhombohedral 36.
(b) A-Tetragonal; B-Monoclinic; C-Triclinic; D-Hexagonal
(c) A-Orthorhombic; B-Trigonal; C-Tetragonal; D-Triclinic
(d) A-Rhombohedral; B-Hexagonal; C-Trigonal;
D-Orthorhombic
31. The axial angles in triclinic crystal system are
(a) α = β = γ = 90° (b) α = γ = 90° ,β ≠ 90°
(c) α ≠ β ≠ γ ≠ 90° (d) α = β = γ ≠ 90°
32. Which crystal system has no rotation of symmetry?
(a) Hexagonal (b) Orthorhombic In the above figure, structure of unit cell represent
(c) Cubic (d) Triclinic that each corner atom is shared between
(a) 8 unit cell (b) 6 unit cell
33. In which of the following structure unit cell shows the
(c) 4 unit cell (d) 2 unit cell
triclinic structure?
37. How much part of any corner constituent particle
γ c
actually belongs to a particular unit cell?
1 1
(a) α (b) (a) th (b) th
4 6
b 1 1
β (c) th (d) th
a 8 10
38. Contribution of each atom per unit cell at face centre
(c) (d) in a fcc unit cell is
(a) 1 (b) 2
(c) 0.5 (d) 2.5
