CBSE Class 12 Chemistry The Solid State Worksheet Set A

Question. The pure crystalline substance on being heated gradually first forms a turbid liquid at constant temperature and still at higher temperature turbidity completely disappears. The behaviour is a characteristic of substance forming
(a) allotropic crystals
(b) liquid crystals
(c) isomeric crystals
(d) isomorphous crystals.
Answer. B

Question. Glass is a
(a) liquid
(b) solid
(c) supercooled liquid
(d) transparent organic polymer.
Answer. C

Question. Most crystals show good cleavage because their atoms, ions or molecules are
(a) weakly bonded together
(b) strongly bonded together
(c) spherically symmetrical
(d) arranged in planes.
Answer. B

Question. The ability of a substance to assume two or more crystalline structures is called
(a) isomerism
(b) polymorphism
(c) isomorphism
(d) amorphism. 
Answer. D

Question. Cation and anion combines in a crystal to form following type of compound
(a) ionic
(b) metallic
(c) covalent
(d) dipole-dipole. 
Answer. A

Question. For two ionic solids CaO and KI, identify the wrong statement among the following.
(a) CaO has high melting point.
(b) Lattice energy of CaO is much larger than that of KI.
(c) KI has high melting point.
(d) KI is soluble in benzene. 
Answer. D

Question. For orthorhombic system axial ratios are a ≠ b ≠ c and the axial angles are
(a) α = β = γ ≠ 90º
(b) α = β = γ = 90º
(c) α = γ = 90º, β ≠ 90º
(d) α ≠ β ≠ γ ≠ 90º
Answer. B

Question. The number of carbon atoms per unit cell of diamond unit cell is
(a) 6
(b) 1
(c) 4
(d) 8 
Answer. D

Question. In a face-centred cubic lattice, a unit cell is shared equally by how many unit cells?
(a) 2
(b) 4
(c) 6
(d) 8
Answer. C

Question. When Zn converts from melted state to its solid state, it has hcp structure, then find the number of nearest atoms.
(a) 6
(b) 8
(c) 12
(d) 4
Answer. C

Question. The fcc crystal contains how many atoms in each unit cell?
(a) 6
(b) 8
(c) 4
(d) 5 
Answer. C

Question. The number of atoms contained in a fcc unit cell of a monatomic substance is
(a) 1
(b) 2
(c) 4
(d) 6 
Answer. C

Question. A compound is formed by cation C and anion A.The anions form hexagonal close packed (hcp) lattice and the cations occupy 75% of octahedral voids. The formula of the compound is
(a) C₄A₃
(b) C₂A₃
(c) C₃A₂
(d) C₃A₄
Answer. D

Question. In calcium fluoride, having the fluorite structure, the coordination numbers for calcium ion (Ca²⁺) and fluoride ion (F^–) are
(a) 4 and 2
(b) 6 and 6
(c) 8 and 4
(d) 4 and 8
Answer. C

Question. The ionic radii of A⁺ and B^– ions are 0.98 × 10^–10 m and 1.81 × 10^–10 m. The coordination number of each ion in AB is
(a) 8
(b) 2
(c) 6
(d) 4
Answer. C

Question. The number of octahedral void(s) per atom present in a cubic close-packed structure is
(a) 1
(b) 3
(c) 2
(d) 4
Answer. A

Question. Structure of a mixed oxide is cubic close packed (ccp). The cubic unit cell of mixed oxide is composed of oxide ions. One fourth of the tetrahedral voids are occupied by divalent metal A and the octahedral voids are occupied by a monovalent metal B. The formula of the oxide is
(a) ABO₂
(b) A₂BO₂
(c) A₂B₃O₄
(d) AB₂O₂ 
Answer. D

Question. A solid compound XY has NaCl structure. If the radius of the cation is 100 pm, the radius of the anion (Y–) will be
(a) 275.1 pm
(b) 322.5 pm
(c) 241.5 pm
(d) 165.7 pm
Answer. C

Question. A compound formed by elements X and Y crystallises in a cubic structure in which the X atoms are at the corners of a cube and the Y atoms are at the facecentres.
The formula of the compound is
(a) XY₃
(b) X₃Y
(c) XY
(d) XY₂
Answer. A

Question. In cube of any crystal A-atom placed at every corners and B-atom placed at every centre of face.
The formula of compound is
(a) AB
(b) AB₃
(c) A₂B₂
(d) A₂B₃
Answer. B

Question.  In crystals of which one of the following ionic compounds would you expect maximum distance between centres of cations and anions?
(a) CsI
(b) CsF
(c) LiF
(d) LiI 
Answer. A

Question. The second order Bragg diffraction of X-rays with λ = 1.00 Å from a set of parallel planes in a metal occurs at an angle 60°. The distance between the scattering planes in the crystal is
(a) 2.00 Å
(b) 1.00 Å
(c) 0.575 Å
(d) 1.15 Å
Answer. D

Question. The intermetallic compound LiAg crystallizes in cubic lattice in which both lithium and silver have coordination number of eight. The crystal class is
(a) face-centred cube
(b) simple cube
(c) body-centred cube
(d) none of these. 
Answer. C

Question. In the fluorite structure, the coordination number of Ca²⁺ ion is
(a) 4
(b) 6
(c) 8
(d) 3
Answer. C

Question. An element has a body centered cubic (bcc) structure with a cell edge of 288 pm. The atomic radius is
(a) √3/4 × 288 pm
(b) √2/4× 288 pm
(c) 4/√3 × 288 pm
(d) 4/√2 × 288 pm
Answer. A

Question. The vacant space in bcc lattice unit cell is
(a) 48%
(b) 23%
(c) 32%
(d) 26%
Answer. C

Question. If a is the length of the side of a cube, the distance between the body-centred atom and one corner atom in the cube will be
(a) 2/√3 a
(b) 4/√3 a
(c) √3/4 a
(d) √3/2 a
Answer. D

Question. A metal crystallises with a face-centred cubic lattice.
The edge of the unit cell is 408 pm. The diameter of the metal atom is
(a) 288 pm
(b) 408 pm
(c) 144 pm
(d) 204 pm
Answer. A

Question. AB crystallizes in a body-centred cubic lattice with edge length ‘a’ equal to 387 pm. The distance between two oppositely charged ions in the lattice is
(a) 335 pm
(b) 250 pm
(c) 200 pm
(d) 300 pm 
Answer. A

Question. Lithium metal crystallises in a body-centred cubic crystal. If the length of the side of the unit cell of lithium is 351 pm, the atomic radius of lithium will be
(a) 151.8 pm
(b) 75.5 pm
(c) 300.5 pm
(d) 240.8 pm
Answer. A

Question. Copper crystallises in a face-centred cubic lattice with a unit cell length of 361 pm. What is the radius of copper atom in pm?
(a) 157
(b) 181
(c) 108
(d) 128
Answer. D

Question. Which of the following statements is not correct?
(a) The number of carbon atoms in a unit cell of diamond is 8.
(b) The number of Bravais lattices in which a crystal can be categorized is 14.
(c) The fraction of the total volume occupied by the atoms in a primitive cell is 0.48.
(d) Molecular solids are generally volatile.
Answer. C

Question. The fraction of total volume occupied by the atoms present in a simple cube is
(a) π/3√2
(b) π 4/√2
(c) π/4
(d) π/6
Answer. C

Question. The pyknometric density of sodium chloride crystal is 2.165 × 10³ kg m^–3 while its X-ray density is 2.178 × 10³ kg m^–3. The fraction of unoccupied sites in sodium chloride crystal is
(a) 5.96
(b) 5.96 × 10^–2
(c) 5.96 × 10^–1
(d) 5.96 × 10^–3
Answer. D

Question. The edge length of face-centred unit cubic cells is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is
(a) 144 pm
(b) 398 pm
(c) 288 pm
(d) 618 pm
Answer. A

Question. Iron exhibits bcc structure at room temperature. Above 900°C, it transforms to fcc structure. The ratio of density of iron at room temperature to that at 900°C (assuming molar mass and atomic radii of iron remains constant with temperature) is
(a) √3/√2
(b) 4 √3/3 √2
(c) 3 √3/4 √2
(d) 1/2
Answer. C

Question. Lithium has a bcc structure. Its density is 530 kg m^–3 and its atomic mass is 6.94 g mol^–1.Calculate the edge length of a unit cell of lithium metal. (NA = 6.02 × 10²³ mol^–1)
(a) 527 pm
(b) 264 pm
(c) 154 pm
(d) 352 pm
Answer. D

Question. A metal has a fcc lattice. The edge length of the unit cell is 404 pm. The density of the metal is 2.72 g cm^–3.
The molar mass of the metal is (NA Avogadro’s constant = 6.02 × 1023 mol^–1)
(a) 27 g mol^–1
(b) 20 g mol^–1
(c) 40 g mol^–1
(d) 30 g mol^–1
Answer. A

Question. CsBr crystallises in a body-centred cubic lattice.The unit cell length is 436.6 pm. Given that the atomic mass of Cs = 133 and that of Br = 80 amu and Avogadro number being 6.02 × 10²³ mol^–1, the density of CsBr is
(a) 4.25 g/cm³
(b) 42.5 g/cm³
(c) 0.425 g/cm³
(d) 8.25 g/cm³
Answer. A

Question. An element (atomic mass = 100 g/mol) having bcc structure has unit cell edge 400 pm. The density of element is
(a) 7.289 g/cm³
(b) 2.144 g/cm³
(c) 10.376 g/cm³
(d) 5.188 g/cm³
Answer. D

Question. Formula of nickel oxide with metal deficiency defect in its crystal is Ni_0.98O. The crystal contains Ni²⁺ and Ni³⁺ ions. The fraction of nickel existing as Ni²⁺ ions in the crystal is
(a) 0.96
(b) 0.04
(c) 0.50
(d) 0.3
Answer. A

Question. The correct statement regarding defects in crystalline solids is
(a) Frenkel defects decrease the density of crystalline solids
(b) Frenkel defect is a dislocation defect
(c) Frenkel defect is found in halides of alkaline metals
(d) Schottky defects have no effect on the density of crystalline solids. 
Answer. B

Question. The appearance of colour in solid alkali metal halides is generally due to
(a) interstitial positions
(b) F-centres
(c) Schottky defect
(d) Frenkel defect. 
Answer. B

Question. Schottky defect in crystals is observed when
(a) density of the crystal is increased
(b) unequal number of cations and anions are missing from the lattice
(c) an ion leaves its normal site and occupies an interstitial site
(d) equal number of cations and anions are missing from the lattice.
Answer. D

Question. Ionic solids, with Schottky defects, contain in their structure
(a) cation vacancies only
(b) cation vacancies and interstitial cations
(c) equal number of cation and anion vacancies
(d) anion vacancies and interstitial anions.
Answer. C

Question. Which is the incorrect statement?
(a) Density decreases in case of crystals with Schottky defect.
(b) NaCl(s) is insulator, silicon is semiconductor, silver is conductor, quartz is piezoelectric crystal.
(c) Frenkel defect is favoured in those ionic compounds in which sizes of cation and anions are almost equal.
(d) FeO0.98 has non-stoichiometric metal deficiency defect. 
Answer. C,D

Question. With which one of the following elements silicon should be doped so as to give p-type of semiconductor?
(a) Selenium
(b) Boron
(c) Germanium
(d) Arsenic 
Answer. B

Question. If NaCl is doped with 10^–4 mol % of SrCl₂, the concentration of cation vacancies will be
(NA = 6.02 × 10²³ mol^–1)
(a) 6.02 × 10¹⁶ mol^–1
(b) 6.02 × 10¹⁷ mol^–1
(c) 6.02 × 10¹⁴ mol^–1
(d) 6.02 × 10¹⁵ mol^–1
Answer. B

Question. If we mix a pentavalent impurity in a crystal lattice of germanium, what type of semiconductor formation will occur?
(a) n-type semiconductor
(b) p-type semiconductor
(c) Both (a) and (b)
(d) None of these 
Answer. A

Question. On doping Ge metal with a little of In or Ga, one gets
(a) p-type semiconductor
(b) n-type semiconductor
(c) insulator
(d) rectifier.
Answer. A

Very Short Answer

Question. What is amorphous silicon? 
Answer. Amorphous silicon is one of the best photovoltaic material available for conversion of sunlight into electricity.

Question. Why there is anisotropy in crystals? 
Answer. Anisotropy in crystals is due to the different arrangement of particles along with different directions.

Question. Define intermolecular forces? 
Answer. The intermolecular force is the sum of all the forces between two neighbouring molecules.

Question. Why do solids have a definite volume and shape? 
Answer. Solids have a definite volume and shape because particles in a solid vibrate around fixed locations.

Question. What are giant molecules? 
Answer. A substance containing a large number of atoms which are covalently bonded, is called a giant molecule

Short Answer

Question. Why amorphous solid is called super cooled liquid? 
Answer. The amorphous solids are called as super cooled liquid which allows molecules in the material to continue to move but in very less large time and as it does not form a crystalline structure or we can say that they have a tendency to flow like liquids i.e. why they are called as pseudo solids or super cooled liquids.

Question. What do you understand by term crystal lattices? 
Answer. A crystal lattice is the arrangement of these atoms, or groups of atoms, in a crystal.These atoms or groups of atoms are commonly referred to as points within a crystal lattice, for example: a crystal lattice is the naturally forming structure of quartz in silica

Question. What are the characteristics properties of the solid state? 
Answer. The characteristic properties of the solid state are:
1. They have definite mass, volume and shape.
2. Intermolecular distances are short.
3. Intermolecular forces are strong.
4. They are incompressible and rigid.

Question. Why solids can be classified as crystalline or amorphous? 
Answer. Solids can be classified into two types: crystalline and amorphous. Crystalline solids are the most common type of solid. They are characterized by a regular crystalline organization of atoms that confer a long-range order. Amorphous, or non- crystalline, solids lack this long-range order.

Question. Define crystalline solids? 
Answer. A crystal or crystalline solid is a solid material whose constituents, such as atoms, molecules or ions, are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions, for example: diamond, quartz. .

Long Answer

Question. Explain the different types of solids? 
Answer. The different types of solids are:
1. Molecular solids: Molecular solids are solids that are essentially collections of molecules held together by intermolecular forces. Molecular solids are made up of atoms or molecules held together by London dispersion forces, dipole-dipole forces, or hydrogen bonds. Characterized by low melting points and flexibility and are poor conductors. The molecular solids further sub divided into: non-polar molecular solids, polar molecular solids and hydrogen bonded molecular solids.
2. Ionic solids: Ionic Solids are solids composed of oppositely charged ions. They consist of positively charged cations and negatively charged anions. When Ionic Solids are dissolved in water the cations and the anions separate, they become free to move about in the water allowing the solution to conduct electrical current.Ionic solids are made up of positive and negative ions and held together by electrostatic attractions. They're characterized by very high melting points and brittleness and are poor conductors in the solid state. An example of an ionic solid is table salt, NaCl.
3. Metallic solids: Metallic solids are solids composed of metal atoms that are held together by metallic bonds. These bonds are like huge molecular orbitals that span across the whole solid. This means the electrons in metallic solids are delocalized. They are not just held between couples of atoms in a sigma bond.
4. Covalent or network solids: A network solid or covalent network solid is a chemical compound or element in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material. In a network solid there are no individual molecules, and the entire crystal or amorphous solid may be considered a macromolecule.

Question. State the difference between crystalline solids and amorphous solids? 
Answer. 1. Crystalline solids have definite and regular geometry due to the orderly arrangement of atoms or ions whereas amorphous solids do not have an ordered
structure; they lack any pattern or arrangement of atoms or ions or any geometrical shape.
2. Crystalline solids have a definite heat of fusion, thus regarded as true solids whereas amorphous solids have no characteristic heat of fusion, thus regarded as super cooled liquids or pseudo-solids.
3. Crystalline solids have a sharp melting point, where it changes into the liquid state whereas amorphous solids do not have a sharp melting point.
4. Crystalline solids have covalent bonds, ionic bonds, Van der Waal’s bonds and metallic bonds whereas amorphous solids have covalently bonded networks.
5. Crystalline solids are anisotropic and, due to which, their physical properties are different in different directions whereas amorphous solids are isotropic because of having the same physical properties in all directions.

Question. Write short note on unit cells? 
Answer. A unit cell is the most basic and least volume consuming repeating structure of any solid. It is used to visually simplify the crystalline patterns solids arrange themselves in. When the unit cell repeats itself, the network is called a lattice, opposite faces of a unit cell are parallel and The edge of the unit cell connects equivalent points. A unit cell is characterized by six parameters. These parameters are three edges (a, b and c) and angles between them (α, β and γ). Dimensions along the edges of a unit cell is represented by a, b and c. Edges of unit cell may or may not be mutually perpendicular. A unit cell is the smallest repeating portion of a crystal lattice. Unit cells occur in many different varieties, the cubic crystal system is composed of three different types of unit cells: (1) simple cubic, (2) face-centred cubic and (3) body-centred cubic. Unit cells are important for two reasons. First, a number of metals, ionic solids, and intermetallic compounds crystallize in cubic unit cells. Second, it is relatively easy to do calculations with these unit cells because the cell-edge lengths are all the same and the cell angles are all 90.

Question. State the difference between molecular solid and covalent network solid? 
Answer. 1. Molecular solid is a solid compound containing molecules held together via Van der Waal forces whereas compound network solid are a solid compounds containing atoms bonded to each other via covalent chemical bond.
2. Molecular solid is relatively soft whereas covalent network solid is very hard.
3. In molecular solid chemical bonds are formed in Van der Waal forces between molecules whereas in covalent network bond chemical bonds are formed in covalent bonds between atoms.
4. In molecular solid the electrical conductivity is with electrical insulators whereas in covalent network solid the electrical conductivity is with low electrical conductivity at liquid state and electrical conductivity at solid phase may vary.
5. In molecular solid the melting point is relatively low whereas in covalent network solid melting point is very high.

Question. State the difference between ionic solids and metallic solids?
Answer. 1. Ionic solids are chemical compounds containing cations and anions whereas metallic solids are solid compounds containing metal atoms and electrons around them.
2. In ionic solids the electrical conductivity is electrical insulators whereas in metallic solids the electrical conductivity is highly conductive.
3. Ionic solids are hard and brittle whereas metallic solids are hard, ductile and malleable.
4. Composition of ionic solids is made up of cations and anions whereas composition is made up of metal ions and electrons.
5. Ionic solids bonding are with electrostatic attraction forces whereas metallic solids bonding only with metallic bonds.

Please click on below link to download CBSE Class 12 Chemistry The Solid State Worksheet Set A