Chapter 1 Solid State

Question 1. Which of the following conditions favours the existence of a substance in the solid state?

(i) High temperature

(ii) Low temperature

(iii) High thermal energy

(iv) Weak cohesive forces

Question 2. Which of the following is not a characteristic of a crystalline solid?

(i) Definite and characteristic heat of fusion.

(ii) Isotropic nature.

(iii) A regular periodically repeated pattern of arrangement of constituent particles in the entire crystal.

(iv) A true solid

Question 3. Which of the following is an amorphous solid?

(i) Graphite (C)

(ii) Quartz glass ($SiO_2$)

(iii) Chrome alum

(iv) Silicon carbide (SiC)

Question 4. Which of the following arrangements shows schematic alignment of magnetic moments of antiferromagnetic substances?

(i)

(ii)

(iii)

(iv)

Question 5. Which of the following is true about the value of refractive index of quartz glass?

(i) Same in all directions

(ii) Different in different directions

(iii) Cannot be measured

(iv) Always zero

Question 6. Which of the following statement is not true about amorphous solids?

(i) On heating they may become crystalline at certain temperature.

(ii) They may become crystalline on keeping for long time.

(iii) Amorphous solids can be moulded by heating.

(iv) They are anisotropic in nature.

Question 7. The sharp melting point of crystalline solids is due to __________.

(i) a regular arrangement of constituent particles observed over a short distance in the crystal lattice.

(ii) a regular arrangement of constituent particles observed over a long distance in the crystal lattice.

(iii) same arrangement of constituent particles in different directions.

(iv) different arrangement of constituent particles in different directions.

Question 8. Iodine molecules are held in the crystals lattice by ____________.

(i) london forces

(ii) dipole-dipole interactions

(iii) covalent bonds

(iv) coulombic forces

Question 9. Which of the following is a network solid?

(i) $SO_2$ (Solid)

(ii) $I_2$

(iii) Diamond

(iv) $H_2O$ (Ice)

Question 10. Which of the following solids is not an electrical conductor?

(A) Mg (s)

(B) TiO (s)

(C) $I_2$ (s)

(D) $H_2O$ (s)

(i) (A) only

(ii) (B) Only

(iii) (C) and (D)

(iv) (B), (C) and (D)

Question 11. Which of the following is not the characteristic of ionic solids?

(i) Very low value of electrical conductivity in the molten state.

(ii) Brittle nature.

(iii) Very strong forces of interactions.

(iv) Anisotropic nature.

Question 12. Graphite is a good conductor of electricity due to the presence of __________.

(i) lone pair of electrons

(ii) free valence electrons

(iii) cations

(iv) anions

Question 13. Which of the following oxides behaves as conductor or insulator depending upon temperature?

(i) TiO

(ii) $SiO_2$

(iii) $TiO_3$

(iv) MgO

Question 14. Which of the following oxides shows electrical properties like metals?

(i) $SiO_2$

(ii) MgO

(iii) $SO_2$(s)

(iv) $CrO_2$

Question 15. The lattice site in a pure crystal cannot be occupied by _________.

(i) molecule

(ii) ion

(iii) electron

(iv) atom

Question 16. Graphite cannot be classified as __________.

(i) conducting solid

(ii) network solid

(iii) covalent solid

(iv) ionic solid

Question 17. Cations are present in the interstitial sites in __________.

(i) Frenkel defect

(ii) Schottky defect

(iii) Vacancy defect

(iv) Metal deficiency defect

Question 18. Schottky defect is observed in crystals when __________.

(i) some cations move from their lattice site to interstitial sites.

(ii) equal number of cations and anions are missing from the lattice.

(iii) some lattice sites are occupied by electrons.

(iv) some impurity is present in the lattice.

Question 19. Which of the following is true about the charge acquired by p-type semiconductors?

(i) positive

(ii) neutral

(iii) negative

(iv) depends on concentration of p impurity

Question 20. To get a n-type semiconductor from silicon, it should be doped with a substance with valence__________.

(i) 2

(ii) 1

(iii) 3

(iv) 5

Question 21. The total number of tetrahedral voids in the face centred unit cell is __________.

(i) 6

(ii) 8

(iii) 10

(iv) 12

Question 22. Which of the following point defects are shown by AgBr(s) crystals?

(A) Schottky defect

(B) Frenkel defect

(C) Metal excess defect

(D) Metal deficiency defect

(i) (A) and (B)

(ii) (C) and (D)

(iii) (A) and (C)

(iv) (B) and (D)

Question 23. In which pair most efficient packing is present?

(i) hcp and bcc

(ii) hcp and ccp

(iii) bcc and ccp

(iv) bcc and simple cubic cell

Question 24. The percentage of empty space in a body centred cubic arrangement is ________.

(i) 74

(ii) 68

(iii) 32

(iv) 26

Question 25. Which of the following statement is not true about the hexagonal close packing?

(i) The coordination number is 12.

(ii) It has 74% packing efficiency.

(iii) Tetrahedral voids of the second layer are covered by the spheres of the third layer.

(iv) In this arrangement spheres of the fourth layer are exactly aligned with those of the first layer.

Question 26. In which of the following structures coordination number for cations and anions in the packed structure will be same?

(i) $Cl^-$ ion form fcc lattice and $Na^+$ ions occupy all octahedral voids of the unit cell.

(ii) $Ca^{2+}$ ions form fcc lattice and $F^-$ ions occupy all the eight tetrahedral voids of the unit cell.

(iii) $O^{2–}$ ions form fcc lattice and $Na^+$ ions occupy all the eight tetrahedral voids of the unit cell.

(iv) $S^{2–}$ ions form fcc lattice and $Zn^{2+}$ ions go into alternate tetrahedral voids of the unit cell.

Question 27. What is the coordination number in a square close packed structure in two dimensions?

(i) 2

(ii) 3

(iii) 4

(iv) 6

Question 28. Which kind of defects are introduced by doping?

(i) Dislocation defect

(ii) Schottky defect

(iii) Frenkel defects

(iv) Electronic defects

Question 29. Silicon doped with electron-rich impurity forms ________.

(i) p-type semiconductor

(ii) n-type semiconductor

(iii) intrinsic semiconductor

(iv) insulator

Question 30. Which of the following statements is not true?

(i) Paramagnetic substances are weakly attracted by magnetic field.

(ii) Ferromagnetic substances cannot be magnetised permanently.

(iii) The domains in antiferromagnetic substances are oppositely oriented with respect to each other.

(iv) Pairing of electrons cancels their magnetic moment in the diamagnetic substances.

Question 31. Which of the following is not true about the ionic solids?

(i) Bigger ions form the close packed structure.

(ii) Smaller ions occupy either the tetrahedral or the octahedral voids depending upon their size.

(iii) Occupation of all the voids is not necessary.

(iv) The fraction of octahedral or tetrahedral voids occupied depends upon the radii of the ions occupying the voids.

Question 32. A ferromagnetic substance becomes a permanent magnet when it is placed in a magnetic field becuase ________.

(i) all the domains get oriented in the direction of magnetic field.

(ii) all the domains get oriented in the direction opposite to the direction of magnetic field.

(iii) domains get oriented randomly.

(iv) domains are not affected by magnetic field.

Question 33. The correct order of the packing efficiency in different types of unit cells is ________.

(i) fcc < bcc < simple cubic

(ii) fcc > bcc > simple cubic

(iii) fcc < bcc > simple cubic

(iv) bcc < fcc > simple cubic

Question 34. Which of the following defects is also known as dislocation defect?

(i) Frenkel defect

(ii) Schottky defect

(iii) Non-stoichiometric defect

(iv) Simple interstitial defect

Question 35. In the cubic close packing, the unit cell has ________.

(i) 4 tetrahedral voids each of which is shared by four adjacent unit cells.

(ii) 4 tetrahedral voids within the unit cell.

(iii) 8 tetrahedral voids each of the which is shared by four adjacent unit cells.

(iv) 8 tetrahedral voids within the unit cells.

Question 36. The edge lengths of the unit cells in terms of the radius of spheres constituting fcc, bcc and simple cubic unit cell are respectively________.

(i) $2\sqrt{2}r, \frac{4r}{\sqrt{3}}, 2r$

(ii) $\frac{4r}{\sqrt{3}}, 2\sqrt{2}r, 2r$

(iii) $2r, 2\sqrt{2}r, \frac{4r}{\sqrt{3}}$

(iv) $2r, \frac{4r}{\sqrt{3}}, 2\sqrt{2}r$

Question 37. Which of the following represents correct order of conductivity in solids?

(i) $k_{metals} >> k_{insulators} < k_{semiconductors}$

(ii) $k_{metals} << k_{insulators} < k_{semiconductors}$

(iii) $k_{metals} \approx k_{semiconductors} > k_{insulators} = \text{zero}$

(iv) $k_{metals} < k_{semiconductors} > k_{insulators} \neq \text{zero}$

Question 38. Which of the following is not true about the voids formed in 3 dimensional hexagonal close packed structure?

(i) A tetrahedral void is formed when a sphere of the second layer is present above triangular void in the first layer.

(ii) All the triangular voids are not covered by the spheres of the second layer.

(iii) Tetrahedral voids are formed when the triangular voids in the second layer lie above the triangular voids in the first layer and the triangular shapes of these voids do not overlap.

(iv) Octahedral voids are formed when the triangular voids in the second layer exactly overlap with similar voids in the first layer.

Question 39. The value of magnetic moment is zero in the case of antiferromagnetic substances because the domains ________.

(i) get oriented in the direction of the applied magnetic field.

(ii) get oriented opposite to the direction of the applied magnetic field.

(iii) are oppositely oriented with respect to each other without the application of magnetic field.

(iv) cancel out each other’s magnetic moment.

Question 40. Which of the following statements are not true?

(i) Vacancy defect results in a decrease in the density of the substance.

(ii) Interstitial defects results in an increase in the density of the substance.

(iii) Impurity defect has no effect on the density of the substance.

(iv) Frankel defect results in an increase in the density of the substance.

Question 41. Which of the following statements are true about metals?

(i) Valence band overlaps with conduction band.

(ii) The gap between valence band and conduction band is negligible.

(iii) The gap between valence band and conduction band cannot be determined.

(iv) Valence band may remain partially filled.

Question 42. Under the influence of electric field, which of the following statements is true about the movement of electrons and holes in a p-type semi conductor?

(i) Electron will move towards the positvely charged plate through electron holes.

(ii) Holes will appear to be moving towards the negatively charged plate.

(iii) Both electrons and holes appear to move towards the positively charged plate.

(iv) Movement of electrons is not related to the movement of holes.

Question 43. Which of the following statements are true about semiconductors?

(i) Silicon doped with electron rich impurity is a p-type semiconductor.

(ii) Silicon doped with an electron rich impurity is an n-type semiconductor.

(iii) Delocalised electrons increase the conductivity of doped silicon.

(iv) An electron vacancy increases the conductivity of n-type semiconductor.

Question 44. An excess of potassium ions makes KCl crystals appear violet or lilac in colour since ________.

(i) some of the anionic sites are occupied by an unpaired electron.

(ii) some of the anionic sites are occupied by a pair of electrons.

(iii) there are vacancies at some anionic sites.

(iv) F-centres are created which impart colour to the crystals.

Question 45. The number of tetrahedral voids per unit cell in NaCl crystal is ________.

(i) 4

(ii) 8

(iii) twice the number of octahedral voids.

(iv) four times the number of octahedral voids.

Question 46. Amorphous solid can also be called ________.

(i) pseudo solids

(ii) true solids

(iii) super cooled liquids

(iv) super cooled solids

Question 47. A perfect crystal of silicon (Fig. 1.1) is doped with some elements as given in the options. Which of these options show n-type semiconductors?

(i)

(ii)

(iii)

(iv)

Question 48. Which of the following statements are correct?

(i) Ferrimagnetic substances lose ferrimagnetism on heating and become paramagnetic.

(ii) Ferrimagnetic substances do not lose ferrimagnetism on heating and remain ferrimagnetic.

(iii) Antiferromagnetic substances have domain structures similar to ferromagnetic substances and their magnetic moments are not cancelled by each other.

(iv) In ferromagnetic substances all the domains get oriented in the direction of magnetic field and remain as such even after removing magnetic field.

Question 49. Which of the following features are not shown by quartz glass?

(i) This is a crystalline solid.

(ii) Refractive index is same in all the directions.

(iii) This has definite heat of fusion.

(iv) This is also called super cooled liquid.

Question 50. Which of the following cannot be regarded as molecular solid?

(i) SiC (Silicon carbide)

(ii) AlN

(iii) Diamond

(iv) $I_2$

Question 51. In which of the following arrangements octahedral voids are formed?

(i) hcp

(ii) bcc

(iii) simple cubic

(iv) fcc

Question 52. Frenkel defect is also known as ________.

(i) stoichiometric defect

(ii) dislocation defect

(iii) impurity defect

(iv) non-stoichometric defect

Question 53. Which of the following defects decrease the density?

(i) Interstitial defect

(ii) Vacancy defect

(iii) Frankel defect

(iv) Schottky defect

Question 54. Why are liquids and gases categorised as fluids?

Question 55. Why are solids incompressible?

Question 56. Inspite of long range order in the arrangement of particles why are the crystals usually not perfect?

Question 57. Why does table salt, NaCl, some times appear yellow in colour?

Question 58. Why is FeO (s) not formed in stoichiometric composition?

Question 59. Why does white ZnO (s) becomes yellow upon heating?

Question 60. Why does the electrical conductivity of semiconductors increase with rise in temperature?

Question 61. Explain why does conductivity of germanium crystals increase on doping with galium.

Question 62. In a compound, nitrogen atoms (N) make cubic close packed lattice and metal atoms (M) occupy one-third of the tetrahedral voids present. Determine the formula of the compound formed by M and N?

Question 63. Under which situations can an amorphous substance change to crystalline form?

Question 64. Match the defects given in Column I with the statements in given Column II.

Question 65. Match the type of unit cell given in Column I with the features given in Column II.

Question 66. Match the types of defect given in Column I with the statement given in Column II.

Question 67. Match the items given in Column I with the items given in Column II.

Question 68. Match the type of packing given in Column I with the items given in Column II.

Question 69. Assertion : The total number of atoms present in a simple cubic unit cell is one.

Reason : Simple cubic unit cell has atoms at its corners, each of which is shared between eight adjacent unit cells.

Question 70. Assertion : Graphite is a good conductor of electricity however diamond belongs to the category of insulators.

Reason : Graphite is soft in nature on the other hand diamond is very hard and brittle.

Question 71. Assertion : Total number of octahedral voids present in unit cell of cubic close packing including the one that is present at the body centre, is four.

Reason : Besides the body centre there is one octahedral void present at the centre of each of the six faces of the unit cell and each of which is shared between two adjacent unit cells.

Question 72. Assertion : The packing efficiency is maximum for the fcc structure.

Reason : The cordination number is 12 in fcc structures.

Question 73. Assertion : Semiconductors are solids with conductivities in the intermediate range from $10^{–6} – 10^4 ohm^{–1}m^{–1}$.

Reason : Intermediate conductivity in semiconductor is due to partially filled valence band.

Question 74. With the help of a labelled diagram show that there are four octahedral voids per unit cell in a cubic close packed structure.

Question 75. Show that in a cubic close packed structure, eight tetrahedral voids are present per unit cell.

Question 76. How does the doping increase the conductivity of semiconductors?

Question 77. A sample of ferrous oxide has actual formula $Fe_{0.93}O_{1.00}$. In this sample what fraction of metal ions are $Fe^{2+}$ ions? What type of nonstoichiometric defect is present in this sample?