CBSE Class 12 Chemistry Solid State Worksheet Set 02

II) Multiple choice questions.

1. Percentage of empty space in a body centre cubic arrangement is

a) 74 b) 32 c) 26 d) 68

2.The total no of tetrahedral voids in fcc is

a) 6 b) 8 c) 10 d) 12

3. Which of the following statement is/ are not true in the hexagonal close packing.

a) Packing efficiency 74% b) C.N=12

c) Tetrahedral voids of the second layer are covered by the spheres of the third layers.

d) Spheres of the fourth layer are exactly aligned with those of the first layer

4. In which pair most efficient packing is present.

a. hcp & bcc

b. bcc& ccp

c. hcp& ccp

d. bcc& simple cubic

5. In which of the arrangement octahedral voids are formed

a. Hcp

b. bcc

c. fcc

d. simple cubic

III) FILL IN THE BLANKS

1. The C.N of each sphere in hcp is ----------- while that of bcc is __________.

2. An octrahedral void is ----------------times larger than a tetrahedral void.

3. ABAB… type of packing is called---------- where as ABCABC…type of packing is called fcc.

4. For bcc, r=31/2 a /4, then for fcc, r=---------.

Ans: I) a-4, b-1, c-3, d-2

Important Questions for NCERT Class 12 Chemistry Solid State

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. 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/√3a
(b) 4/√3a
(c) √3/4a
(d) √3/2a

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. 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

MCQs Questions for NCERT Class 12 Chemistry Solid State

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. An element crystallising in body centered cubic lattice has an edge length of 500 pm. If its density is 4 g cm-3, the atomic mass of the element (in g mol-1) is (consider NA= 6x1023)
(a) 100
(b) 150
(c) 200
(d) 250

Answer: B

Question. In face centered cubic unit cell, what is the volume occupied
(a) 4Πr3/3
(b) 8Πr3/3
(c) 16Πr3/3
(d) 64r3/3√ 3

Answer: C

Question. Consider the bcc unit cells of the solids 1 and 2 with the position of atoms as shown below . The radius of atoms B is twice that of atoms A . The unit cell edge length is 50% more in solid 2 than 1. What is the approximate packing efficiency in solid 2.    

(a) 45%
(b) 65%
(c) 90%
(d) 75%

Answer: C

Question. A crystalline solid has a cubic structure in which tungsten (W) atoms are located at cubic corners of the unit cell, oxygen atoms at edges of the cube and sodium atom at the cube centre. The molecular formula of the compound is
(a) Na2WO₃
(b) NaWO₄
(c) NaWO₃
(d) Na₂WO₄

Answer: C

Question. If ‘a’ stands for edge length of cubic systems: body centered and face centered cubic then the ratio of the radii of the sphere in these systems will be respectively
(a) √ 3 a: a/√ 2
(b) √ 3 a/2: √ 2 a/2
(c) √ 3 a/4:a/2√ 2
(d) √ 3 a: √ 2 a

Answer: C

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. 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. 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. 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. 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

Assertion Reason Based Question :

(a) Assertion and Reason both are correct statements and Reason is correct explanation for Assertion.
(b) Assertion and Reason both are correct statements but Reason is not correct explanation for Assertion.
(c) Assertion is correct statement but Reason is wrong statement.
(d) Assertion is wrong statement but Reason is correct statement.

Question. Assertion : In closed packed structure the number of tetrahedral void is twice the number of atoms present
Reason : Tetrahedral voids are located above each atom in the first layer and below each atom in second layer

Answer: A

Question. Assertion : Semiconductors show some conductivity.
Reason : They have only small difference in energy between the filled valence band and empty conduction band.

Answer: A

Question. Assertion: Fe₃O₄ is an example of ferrimagnetism.
Reason: Ferrimagnetism has resulting net magnetic moment

Answer: B

Question. Assertion : Distance between the nearest lattice points in BCC is greater than the same in FCC having same edge length
Reason: FCC has greater packing efficiency than BCC.

Answer: A

ONE MARK QUESTIONS

1.What is meant by forbidden zone in reference to band theory of solids?

2. Refractive index of a solid is observed to have the same value along all directions. Comment on the nature of this solid. Would it show cleavage property?

3. Write the formula of a compound in which the element Y forms ccplattice and atoms of X occupies 1/3^rd of tetrahedral voids. 

4. An alloy of gold and cadmium crystallizes with a cubic structure in which gold atoms occupies the corners and cadmium atoms fit into the face center. Assign formula of this alloy. 

TWO MARK QUESTIONS

1.Iron has a bcc unit cell with a cell dimension of 286.65pm. The density of Fe is7.874gcm^-3. Use this information to calculate Avogadro’s number. (Fe = 55.845u)

2.Silver crystallizes in fcc unit cell. If the edge length of Ag atom is 4.07 x 10-8 cm and density of silver is 10.5 g cm^-3calculate the atomic mass of silver. 

3.An element crystallizes in fcc structure with edge length 200pm. Calculate the density if 200g of the element contains 24 x 10²³ atoms.

4.How are the following properties of crystal affected by Schottky and Frenkel defect:
a) Density
b) Electrical conductivity

5.a) Why does the presence of excess of lithium make LiCl crystals pink?
b) Calculate the number of atoms in cube based unit cell having one atom on each corner and two atoms on its each body diagonal.

2. Explain the following properties giving suitable examples:
a) Ferromagnetism
b) Para magnetism
c) Ferrimagnetism 

3. An element A crystallizes in fcc structure. 208g of it have 4.28 x 10²⁴ atoms. Calculate the edge length if the density is 7.2g/cc.

4. An element crystallizes in cubic structure. The edge length of the unit cell is 350pm. If its molar mass is 6.94g/mole, and the density 0.534g/cc, how many atoms are present in one unit cell of the element?

5. Define the following : (i) Schottky defect (ii) Frenkel defect (iii) F-centre 

FIVE MARKS QUESTIONS

1. Differentiate between:
a) Face centered and end centered unit cells
b) Ferromagnetic and ferrimagnetic substances
c) n-type and p-type semiconductors
d) Tetragonal and orthorhombic unit cells
e) Crystal lattice and unit cell

1 MARK QUESTIONS

Question. What type of solids are electrical conductors, malleable and ductile?
Answer : metallic

Question. Give the significance of lattice point.
Answer : It signifies position of constituent particles of the unit cell

Question. Name the parameters that characterize the unit cell
Answer : edge lengths a,b,c and angles (alpha,beta,&gamma)

Question. What is the two dimensional coordination number of a molecule in square close packed structure.
Answer : 4

Question. Which of the following lattice has the highest packing efficiency, (I) simple cubic (II) BCC (III) HCP
Answer : hcp

Question. What type of stoichiometric defect is shown by ( i) ZnS (ii) AgBr
Answer : (i). frenkel (ii). Both schottky and frenkel

Question. What type of substances make better permanent magnets? Justify your answer.
Answer : ferromagnetic, domains aligned in the same direction

Question. Why glass is considered as super cooled liquid?
Answer : pseudo solid or shows fluidity

Question. Why KCl appear s pink when heated in K vapors ?
Answer : F- centres

Question. Give the relationship between density and edge length in an unit cell.
Answer : density = Z .M/a³.NA

Question. what is F-centre?
Answer : vacant anionic sites occupied by electrons

Question. Give the coordination number of fcc structure.
Answer : 12

Question. Give an example of a solid that shows both schottky and frenkel defect
Answer : AgBr

Question. What defect is observed when CdCl₂ is doped with AgCl?
Answer : impurity defect

Question. Give an example of a network solid.
Answer : SiC

Question. Give an example each of 13-15 & 12-16 compounds
Answer : AlP,ZnS

Question. How is quartz different from quartz glass?
Answer : long range order of constituents in quartz, short range order of constituents in quartz glass

Question. What is a semiconductor?
Answer : energy gap between valence band and conduction band is small or conductivity range is between 10^-6ohm^-1 m^-1 to 10⁴ ohm^-1 m-1

Question. FeO is mostly found with a composition of Fe0_.95 O _1.00 . Why?
Answer : Metal deficiency defect

Question. What is a n-type semiconductor?
Answer : When a group -14 element is doped with gr-15 element an electron 0f gr-15 element remains as free electron. That increases conductivity

2 MARKS QUESTIONS

Question. The edge length of a unit cell having molecular weight 75g/mol is 5 A⁰ which crystallizes in bcc lattice . If the density is 2g/cc then find the radius of the metal atom.
Answer : r = 216.5pm

Question. Potssium crystallizes in bcc lattice. Calculate the approximate number of unit cell in 1gm of potassium. (atomic mass of K = 39)
Answer : 7.72*10²¹

Question. A compound is formed by two elements M &N .The element N forms ccp & atoms of M occupy 1/3rd of tetrahedral voids. What is the formula of the compound?
Answer : M₂N₃

Question. A unit cell consists of a cube in which there are atoms A at the corners and atoms B at the face centres.Two A atoms are missing from the two corners of a unit cell.Whati is the formula of the compound.
Answer : AB₄

Question. Analysis shows that nickel oxide has formula Ni _0.98 O _1.00 .What fraction of nickel exist as Ni ²⁺ and Ni ³⁺.
Answer : Ni ²⁺ = 96% Ni ³⁺ = 4%

Question. If NaCl is doped with 10^-3 mol % of SrCl ₂ . What is the concentration of cation vacancy?
Answer : 10 ^-3 /100 mol = 10^-5 x 6.022 x 10²³ = 6.022 x 10¹⁸

Question. Under what conditions will sodium chloride conduct electricity
Answer : molten state or in aq. Solution

Question. Name the binding force in each of the following. (a) Molecular (b) Ionic (c) Covalent (d) Metallic.
Answer : (a) vanderwaals forces (b) electrostatic (c) covalent bond (d) metallic bond

Question. Differentiate between anisotropy & isotropy by giving examples.
Answer : Substances show different properties in diffrent direction & the reverse

Question. Derive the relationship between edge length and radius of atom in fcc unit cell.
Answer : a = 2.2 ^1/2 r

3 MARKS QUESTION

Question. Calcium metal crystalises in a fcc lattice with edge length of 0.556nm calculate the density of the metal if it contains , (i) 0.5% frenkel defect (ii) 0.2% schottky defect.
Answer : (i) d =1.5458g cm^-3 (ii)1.5427g cm^-3

Question. How is ferromagnetism different from paramagnetism & antiferromagnetism & explain what type substances show antiferromagnetism
Answer : Attracted strongly by magnetic field ,paramagnetic substances are weakly attracted ,antiferromagnetic substances not attracted

Question. What is electrical conductivity due to in (i) metals (ii) ionic solids (iii) semiconductors
Answer : due to flow of electrons
b. flow of ions in solution or melt and defects in solid
c. due to presence of impurities and defects

Question. What is the difference between schottky defect & frenkel defect .
Answer : Schottjy defect- vacancy defect,density lowers frenkel defect- interstitial defect density is not affected.

Question. How would account for the following
a. Frenkel defcts are not found in alkali metal halides.
b. schottky defects lower the density of related solids.
c. impurity dopped silicon is a semiconductor .
Answer : (i) similar size of cations and anions
(ii) equal no of cations and anions are missing results into decrease in mass
(iii) due to presence of free electrons or creation of positive hole.

Question. Define the following terms in relation to crystaline solids
a. Unit cell
b. co ordination number
c. P- type semiconductor
Answer : (i) it is the smallest portion of the crystal lattice which when repeated in all directions gives the entire lattice.
(ii) Number of nearest neighbour iii) gr-14 doped with gr-13 creates positive hole
 

Important Questions for NCERT Class 12 Chemistry Solid State

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. 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. 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 Ni0.98O. 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. 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. 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. 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

Question. What is photovoltaic cell?
Answer : device which converts sunlight into electrical energy.

Question. What do you mean by the term Doping?
Answer : Introduction of defects in solid by incorporating foreign particles.

Question. What the term 12 – 16 compounds stand for?
Answer : compounds formed by combination of group 12 elements and group 16 elements.e.gZnS

Question. What is the number of tetrahedral voids in a ccp structure of solid?
Answer : 2N or 8

Question. Crystalline solids are anisotropic in nature.comment on this statement.
Answer : a single property differs in different direction in solids.

Question. What is the percentage efficiency of a solid whose particles are having ccp structure?
Answer : 74%

Question. LiCl crystal appears to be pink in colour .Why?
Answer : presence of F – centre .

Question. WhenGe is doped with slight amount of In,what type of semiconductor will be formed?
Answer : p – type semiconductor

Question. Metal deficiency defect with extra anions in interstitial sites can’t be produced in solids.Why?
Answer : usually anions are larger in size and hence donot fit into interstitial sites

Question. The electrical conductivity of semiconductors increases with increase in temperature but in case of metals conductivity decreases with rise in temp. Why?
Answer : kernels makesxibration and creates obstacles in the motion of electrons in case of metals.

Question. The window panes seem to be thicker at the bottom in case of old buildings.what can be the reason?
Answer : Glass is supercooled liquid and has floed under the influence of gravity.

Question. Assign the relationship between edge length (a,b,c) and values of α,β and ϒ for tetragonal unit cell.
Answer : a = b ≠ c, α =β =ϒ =90⁰

Question. Give an example of solid which can exhibit schottky defect as well as frenkel defect.
Answer : AgBr.

Question. Atoms of element A are occupying all the octrahedral voids while atoms of B are in 1/4thtetrahedral voids and atoms of C are arranged in hexagonal arrays .what will be the formula of the compound?
Answer : A₂BC₂

Question. What is the co-ordination number of a particle in ccp structure?
Answer : 12

Question. What happens when Na vapours is passed over crystalline NaCl?
Answer : Appears yellow due to creation of F – centre.

Question. Ferromagnetic and ferrimagneetic solids on heating converted into paramagnetic in nature.justify the reason.
Answer : Due to randomization of electrons.

Question. Gjass is assumed to be supercooledliquid.why?
Answer : Flowing tendency under influence of gravity.

Question. Give an example of solid which has its structure as fluorite type structure. 
Answer : CaF₂

Question. Copper is conducting as such while copper sulphate is conducting only in aqueous solution .why?
Answer : Copper is electronic conductor but copper sulphate is ionic conductor so ions are free only in molten or in aqueous state.

Question. Potassium crystallizes in a BCC Lattice. Find number of unit cells in one gram of potassium. (K = 39u)
Answer : 7.72×10²¹

Question. The edge length of unit cell of a metal having molecular mass 75g/mol is 5A◦ which crystallizes in cubic lattice. If the density is 2g/cc, find the radius of metal atom.
Answer : 216.5pm

Question. The metal Calcium crystallizes in a FCC unit cell with A = 0.556nm. Find the density of the metal if (Ca =40u)
i. It contains 0.2% Frenkel defects
ii. It contains 0.1% Schottky defect.
Answer : i. 1.5463
ii. 1.5448g/cm³

Question. Analysis shows that a metal oxide has an emperical formula M0.96O. Find the percentage of M²⁺ and M³⁺ ion in the sample.
Answer : 91.67%; 8.33%

Question. Metal crystallizes in 2 cubic phases FCC and BCC whose unit cell lengths are 3.5A◦ and 3.0A◦ respectively. Find the ratio of the densities of FCC and BCC.
Answer : 1.259

Question. An element ‘X’ with at mass of 60g/mol has density of 6.23gcm³. If the edge length of its cubic unit cell is 400pm. Identify the type of cubic unit cell. Find the radius of an atom of this element.
Answer : Z = 4; R = 141.4pm

Question. An element with molar mass 2.7×10^-2kg/mol forms a cubic unit cell with edge length 405pm. If the density is 2.7×10³kg/m³. What is the nature of this cubic unit cell?
Answer : 4 FCC

Question. Silver crystallizes in FCC lattice. If edge length of this cell is 4.077×10^-8cm and density us 10.5gm/cm³.
Find the atomic mass of silver.
Answer : 107.12g

Question. Niobium crystallizes in BCC structure. If the density is 8.55g/cm³. Find the radius of niobium using its atomic mass 93u.
Answer : 14.29×10^-7cm

Question. Aluminum crystallizes in cubic close-packed structure gets metallic radius is 125pm.
i. What is the length of the side of unit cell
ii. How many unit cells are there in 1cm³ of Aluminum?
Answer : i. 354pm
ii. 2.26×10²⁸

Question. An element (atomic mass 60) having FCC unit cell has the density of 6.23g/cm³. What is the edge length of this cell?
Answer : 400pm

Question. A BCC unit cell has density 10.3g/cm³ with edge length 314pm. Find atomic mass.
Answer : 96g

Question. Find the type of cubic lattice to which the iron crystal belongs if its unit cell has an edge length of 286pm and density of iron is 7.86g/cm³
Answer : 2 BCC

Question. An element (A) crystallizes in FCC structure, 200g of this element has 4.12×10²⁴ atoms. The density of A is 7.2g/cm³. Find the edge length of unit cell.
Answer : 6.46A◦

Question. Lithium metal has a BCC structure. Its density is 0.53 g/cm³ and its atomic mass is 6.94g/mol. Find the volume.
Answer : 4.348×10^-23cm³

Question. Sodium crystallizes in cubic lattices and the edge of the unit cell 430pm. Find the number of atoms in the unit cell. Density is 0.9623g/cm³
Answer : Z=2

Question. Chromium crystallis3es in BCC structure with edge 286pm. Find atomic radius, number of atoms per unit cell and density.
Answer : 124.27pm; 27.3g/cm³

Question. The nearest neighbor silver atom in the silver crystal are 287pm apart. What is the density of silver? It forms FCC structure and molecular mass of silver is 107.87g/mol.
Answer : 10.72g/cm³

Question. Iron metal has BCC with edge 286.65pm. The density is 7.87 g/cm³. Find Avogadro’s number.
Answer : 6.043×10²³

Question. Silver crystallizes in FCC with side length with side length of 409pm. What is the radius of an atom of silver?
Answer : 144.6pm

Close Packing of Solids

Question. Match the following columns for close packing of solids:
COLUMN-A
(a) Square close packing in two dimensions
(b) Hexagonal close packing in two dimensions
(c) Hexagonal close packing in three dimensions
(d) Cubic close packing in three dimensions

COLUMN-B
(1) Triangular voids
(2) Pattern of spheres is repeated in every fourth layer.
(3) Pattern of spheres is repeated in alternate layers.
(4) Co-ordination number-4

Answer: (a) - 4, (b) - 1, (c) - 3, (d) - 2

Question. Percentage of empty space in a body centre cubic arrangement is
(a) 74
(b) 32
(c) 26
(d) 68
Answer: (b) 32

Question. The total no of tetrahedral voids in fcc is
(a) 6
(b) 8
(c) 10
(d) 12
Answer: (b) 8

Question. Which of the following statement is/ are not true in the hexagonal close packing.
(a) Packing efficiency 74%
(b) C.N=12
(c) Tetrahedral voids of the second layer are covered by the spheres of the third layers.
(d) Spheres of the fourth layer are exactly aligned with those of the first layer
Answer: (d) Spheres of the fourth layer are exactly aligned with those of the first layer

Question. In which pair most efficient packing is present.
(a) hcp & bcc
(b) bcc & ccp
(c) hcp & ccp
(d) bcc & simple cubic
Answer: (c) hcp & ccp

Question. In which of the arrangement octahedral voids are formed
(a) hcp
(b) bcc
(c) fcc
(d) simple cubic
Answer: (c) fcc

Question. The C.N of each sphere in hcp is ----------- while that of bcc is __________.

Answer: 12 & 8

Question. An octahedral void is ----------------times larger than a tetrahedral void.

Answer: two

Question. ABAB… type of packing is called---------- where as ABCABC…type of packing is called fcc.

Answer: HCP

Question. For bcc, r=\( 3^{1/2} a /4 \), then for fcc, r=---------.

Answer: \( \sqrt{2} a/4 \)

Classification of Solids

Question. Match the following columns for classification of solids:
COLUMN-A
(a) Ionic crystal
(b) Metallic crystal
(c) Covalent crystal
(d) Non polar crystal
(e) Hydrogen bonded crystal

COLUMN-B
(1) Graphite
(2) Ice
(3) MgO
(4) Gold
(5) Dry ice

Answer: (a) - 3, (b) - 4, (c) - 1, (d) - 5, (e) - 2

Question. Which of the following is a network solid?
(a) \( \text{I}_2 \)
(b) \( \text{SO}_2 \) (solid)
(c) Diamond
(d) Argon
Answer: (c) Diamond

Question. Which of the following is not an electrical conductor?
(a) only b
(b) only c
(c) a & d
(d) b, c & d
Answer: (c) a & d

Question. Which of the following is not a characteristic of a crystalline solid?
(a) True solid
(b) long range order
(c) isotropic in nature
(d) definite heat of fusion
Answer: (c) isotropic in nature

Question. A solid is very hard, electrical insulator in solid state as well as in molten state & melts at extremely high temperature . It may be
(a) covalent solid
(b) metallic solid
(c) molecular solid
(d) ionic solid
Answer: (a) covalent solid

Question. Iodine molecules are held in crystals by
(a) London forces
(b) coulombic forces
(c) dipole- dipole interactions
(d) covalent bonds
Answer: (a) London forces

Question. Graphite is a good conductor due to presence of -----------.

Answer: Free electrons

Question. Glass is a ---------- solid as it shows fluidity.

Answer: Pseudo solid

Question. If the electrical conductivity is same in all direction through a solid the substance is an amorphous solid & this property is called ------------.

Answer: Isotropy

Defects in Crystals

Question. Match the following columns for defects in crystals:
COLUMN-A
(a) Schottky defect
(b) Doping silicon with aluminium
(c) Doping silicon with arsenic
(d) Heating NaCl crystal in presence of sodium vapour.
(e) Impurity defects

COLUMN-B
(1) Crystals become coloured
(2) n-type of semiconductors are formed
(3) NaCl with \( \text{Sr}^{+2} \) & some cationic sites vacant.
(4) Density of the crystals decreases
(5) p-type of semiconductor is formed

Answer: (a) - 4, (b) - 5, (c) - 2, (d) - 1, (e) - 3

Question. Which kind of defects are introduced by doping?
(a) dislocation defect
(b) Schottky defect
(c) Frenkel defect
(d) Electronic defects
Answer: (a) dislocation defect

Question. Which of the following is also known as dislocation defect?
(a) Schottky defect
(b) Frenkel defect
(c) nonstoichiometric defect
(d) simple interstitial defect
Answer: (b) Frenkel defect

Question. Which of the following defects are shown by AgBr?
(a) i
(b) ii
(c) iii
(d) iv
Answer: (a) i

Question. To get an n-type of semiconductor from silicon it should be doped with a substance with valence --------electrons
(a) 1
(b) 2
(c) 3
(d) 5
Answer: (d) 5

Question. Schottky defect is observed in the crystal when
(a) some cations move from their lattice sites to interstitial sites
(b) equal number of cations and anions are missing from the lattice
(c) some lattice sites are occupied by the electrons
(d) some impurity is present in the lattice
Answer: (b) equal number of cations and anions are missing from the lattice

Question. NaCl crystals have some yellow colour is due to the presence of -----------.

Answer: F-centre

Question. The process of adding impurities to a crystalline substance so as to change its properties like conductivities etc is called ----------------

Answer: doping

Question. Frenkel defect is shown by crystals having low coordination number & ---------- difference in the size of the cations & anions.

Answer: large

Question. Schottky defect in ionic crystals always results in --------- of density.

Answer: decrease

Question. ----------- crystal defect is produced when NaCl is doped with \( \text{MgCl}_2 \).

Answer: impurity defect

Solid State - Practice Cards

Question. The excess of lithium in LiCl makes it pink is due to -----------------------------

Answer: F-centre

Question. The compound that shows both Schottky and Frenkel defect is -----------------------

Answer: AgBr

Question. Doping ---------(minimizes, maximizes) the forbidden energy gap.

Answer: minimizes

Question. The forbidden energy is maximum in -------- ( Ge, Mg, NaCl, Ge doped with In )

Answer: NaCl

Question. Which one show metal excess defects ( FeO, ZnO)

Answer: ZnO

Question. When an electron is trapped in an anion vacant centre, it is called ------------------------.

Answer: F-centre

Question. Si, Ge can be doped with a group -------------- elements to produce p-type semiconductor. ( Gp- 12,13,14,15)

Answer: 13

Question. Solar cell is an efficient -------------------------- ( photo-diode, photo-triode)

Answer: photo-diode

Question. Diode acts as a ------- ( rectifier, amplifier)

Answer: rectifier

Question. ---------------- oxide is like metallic cu in its conductivity and appearance .

Answer: \( \text{ReO}_3 \)

Question. The process of adding an appropriate amount of suitable impurity to increase the conductivity of an intrinsic semi-conductor like Si, Ge is called

Answer: Doping

Question. When in a substance the magnetic moments of the domains are aligned in parallel and antiparallel directions in unequal numbers, the phenomenon observed is called ----------- . (ferromagnetism, anti-ferromagnetism, ferrimagnetism)

Answer: ferrimagnetism

Question. In which type of semi-conductor, electron holes are moving towards negatively charged plate under the influence of electric field? ( p-type, n-type)

Answer: p-type

Question. If an atom is missing from its lattice site and it occupies the interstitial site, the electrical neutrality as well as the stoichiometry of the compound are maintained. This type of defect is called -------------------- defect.

Answer: Frenkel defect

Question. The set of molecular orbitals generated due to overlap of atomic orbitals having very close in energy is called ---------

Answer: Bands

Question. Frenkel defect is shown by the crystals having --------------- (high, low) co-ordination number and ---- (large, small) difference in the size of the cations and the anions .

Answer: low, large

Question. ---------------- is a covalent crystal ( Iodine, NaCl, ice, Carborundum)

Answer: Carborundum

Question. Which one will show anisotropy? ( quartz, paraffin wax, rubber, quartz glass )

Answer: quartz

Question. ---- solids conducts electricity in molten state but not in solid state. ( molecular, ionic, metallic, covalent)

Answer: ionic

Question. ---------------- solids have very high melting point ( molecular, ionic, metallic, covalent)

Answer: covalent

Question. Solar cell is an efficient ------------------- ( photo-diode, photo-triode)

Answer: photo-diode

Question. Photovoltaic material is -------------------- ( Amorphous silicon, Pure silicon crystal)

Answer: Amorphous silicon

Question. Some of the glass from ancient civilizations which are with us are milky in appearance due to

Answer: Due to some crystallization

Question. In end-centred unit cell of an atomic substance there are four atoms per unit cell. [True/False]

Answer: False

Question. In rock-salt structure, the number of formula units per unit cell is four. [True/False]

Answer: True

Question. Schottky defects disturb the ratio of cations and anions in the compound. [True/False]

Answer: False

Question. NaCl is a paramagnetic substance. [True/False]

Answer: False

Question. A compound having radius ratio (r+/r-) in the range 0.732—1 generally has CsCl structure. [True/False]

Answer: True

Question. \( \text{Fe}_3\text{O}_4 \) is ferrimagnetic. Among the three type of arrangement, hcp, ccp, and bcc, the most efficient packing is bcc. [True/False]

Answer: False

Question. If the radius ratio is in the range 0.225—0.414 the cation prefers to be present in an octahedral void. [True/False]

Answer: False

Question. Diamond is an example of atomic solid. [True/False]

Answer: True

Question. Orthorhombic unit cell has least symmetry. [True/False]

Answer: False

Question. F-centre is a type of stoichiometric defect. [True/False]

Answer: True

Question. 14 kinds of space lattices are possible in the crystal. [True/False]

Answer: True

Question. Pure alkali halides show Frenkel Defects. [True/False]

Answer: True

Question. When temperature increases conductivity of semi-conductor decreases. [True/False]

Answer: False

Question. Frenkel defect is shown by ionic substance in which there is a large difference in the size of ions. [True/False]

Answer: True

Question. The existence of different chemical compounds in the same crystalline form is called allotropy. [True/False]

Answer: False