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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Sodium metal crystallises in body centred cubic lattic with cell edge `4.29 Å` .What is the radius of sodium atom ?A. `1.857 xx 10^(-8) cm`B. `2.371 xx 10^(-7) cm`C. `3.817 xx 10^(-8) cm`D. `9.312 xx 10^(-8) cm` |
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Answer» Correct Answer - a Radius of Na (if bcc lattile) `= sqrt(3a)/(4) = (sqrt(3) cc 4.29)/(4)` `= 1.8574 Å = 1.8574 xx 10^(-8)cm` |
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| 52. |
The interionic distance for cesium chloride crystal will beA. aB. a/2C. `sqrt3 a//2`D. `2a//sqrt3` |
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Answer» Correct Answer - C CsCl have simple cubic structure. In this structure body idagenal of simple cube `sqrt3 a = 2 xx (r_(CS^(+)) + r_(Cl^(-)))` So interionic distance `= 2 xx (r_(CS^(+)) + r_(Cl^(-)))` |
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| 53. |
The edge length of a face centred cubic cell of an ionic substance is `508` pm .If the radius of the cation is 110 pm the radius of the anion isA. 114 pmB. 288 pmC. 398 pmD. 618 pm |
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Answer» Correct Answer - a For fcc , `r^(+) + r^(-) = (a)/(2)` `110 + r^(-) = (500)/(2)` `r^(-) = 144` pm |
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| 54. |
The interionic distance for cesium chloride crystal will beA. `a`B. `(a)/(2)`C. `sqrt(3a)/(2)`D. `(2a)/(sqrt(3)` |
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Answer» Correct Answer - c As `CaCI` is body - centred `d = sqrt(3a)//2` |
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| 55. |
An elementoccurring in the bcc structure has `12.08 xx 10^(23)` unit cells .The total number of atoms of the element in these cells will beA. `24.16 xx 10^(23)`B. `36.18 xx 10^(23)`C. `6.04 xx 10^(23)`D. `12.08xx 10^(23)` |
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Answer» Correct Answer - a There are two atoms is a has unit cell So number of atoms in `12.08 xx 10^(23)` unit cells `= 2 xx 12.08 xx 10^(23) = 24.16 xx 10^(23) `atom |
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| 56. |
A metallic crystal cystallizes into a lattice containing a sequence of layers `ABABAB…`. Any packing of spheres leaves out voids in the lattice. What percentage by volume of this lattice is empty spece? |
| Answer» Correct Answer - Refer Section 1.22. | |
| 57. |
Predict the structure of MgO crystal and the co-ordination number of the cation in which the radii of the cation and anion are 65 pm and 140 pm respectively. |
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Answer» Radius ratio, `(r^(+))/(r^(-))=(("65pm"))/(("140pm"))=0.464` Since the radius ratio falls in the range `0.414-0.732`, the co-ordination of the cation is 6 and its expected structure is octahedral. |
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| 58. |
Predict coordination umber of the cation in crystals of the following compounds : `(1). MgO:r_(c)=0.65Å, r_(a)=1.40Å` `(2). MgS:r_(c)=0.65Å, r_(a)=1.84Å`A. 6,4B. 4,6C. 3,4D. 6,8 |
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Answer» Correct Answer - A |
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| 59. |
In a cubic unit cell, seven of the eight corners are occupied by atoms A and centres of faces are occupied by atoms B. The general formula of the compound is:A. `A_(7)B_(6)`B. `A_(7)B_(12)`C. `A_(7)B_(24)`D. `A_(24)B_(7)` |
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Answer» Correct Answer - C |
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| 60. |
LiCl has rock salt structure, with an edge length of `6.0A^(@)`. If anions are in contact, the inoic radius of chloride ion isA. `2.12A^(@)`B. `1.82A^(@)`C. `4.24A^(@)`D. `3.68^(@)` |
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Answer» Face diagonal `=sqrt(2)a=sqrt(2)xx6=8.484` Also face diagonal =4r `r4=8.484 A^(@)rArrr=(8.484)/(4)=2.121A^(@)` |
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| 61. |
BaO has a rock-salt type structure. When subjected to high pressure, the ratio of the coordination number of `Ba^(+2)` ion to `O^(-2)` changes toA. `4 : 8`B. `8 : 4`C. `8 : 8`D. `4 : 4` |
| Answer» Correct Answer - C | |
| 62. |
An element X (At. Wt. =224) forms FCC lattice. If the edge length of lattice is `4 xx 10^(-8)` cm and the observed density is `2.4 xx 10^(3 kg//m^(3)`. Then the percentage occupancy of lattice point by element X is : `(N_(A) = 6 x 10^(23))`A. 96B. 98C. 99.9D. None of these |
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Answer» Correct Answer - A |
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| 63. |
Which of the following statements is correct in the rock-salt structure of ionic compounds?A. Co-ordination number of cation is four and anion is sixB. Co-ordination number of cation is six and anion is fourC. Co-ordination number of each cation and anion in fourD. Co-ordination number of each cation and anion in six |
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Answer» Correct Answer - D |
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| 64. |
Which of the following statement is correct for the body-centred cubic structure of an ionic compound?A. Co-ordination number of each cation and anion is twoB. Co-ordination number of each cation and anion in fourC. Co-ordination number of each cation and anion in sixD. Co-ordination number of each cation and anion in eight |
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Answer» Correct Answer - D |
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| 65. |
`A_(2)B` molecules`(" molar mass " = 259.8 g//"ml")` crystallises in a hexagonal lattice as shown in figure .The lattic constants were `a=5 Å` and `b=8 Å` . If denstiy of crystal is `5 g//cm^(3)` then how many molecules are contained in given unit cell ? `(" Use" N_(A) = 6xx10^(23))` A. 6B. 4C. 3D. 2 |
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Answer» Correct Answer - D |
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| 66. |
Percentage of free space in cubic close packed struchure and in body centred structure are respectively.A. `30%` and `26%`B. `26%` and 32%`C. `32%` and `48%`D. `48%` and `26%` |
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Answer» Correct Answer - B Packing fraction of cubic close packing and body centred packing are `0.74` and `0.68` respectively. So, vacant space is `26%` and `32%` respectively. |
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| 67. |
Percentage of free space in cubic close packed struchure and in body centred structure are respectively.A. 48% and 26%B. 30% and 26%C. 26% and 32%D. 32% and 48% |
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Answer» Correct Answer - C For FCC or CCP `4r=sqrt(2)a` `P . F =(nxx(4)/(3)pir^(3))/(a^(3))` `n=4,a=2sqrt(2r)` P.F. = 74% Free space = 100 - 74 = 26% For BCC `4r=sqrt(3)a` P.E. `=(2xx(4)/(3)pir^(3))/((4)/(sqrt(3))r)^(3)` P.F. = 68% Free space = 32% |
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| 68. |
Percentage of free space in cubic in a body- centred cubic unit cell is .A. 74B. 68C. 32D. 26 |
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Answer» Correct Answer - C packing efficiency for bcc arrangement is 68 % which represents total filled space in the unit cell hence empty space in body centred arrangement is 10-68 = 32 % note :- here ,empty space in bcc arrangement is asked therefore empty space in any crystal packing can be empty space in unit cell =100- packing efficiency |
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| 69. |
If Agl crystallises in zinc blende structure with `I^(-)` ions at lattice points. What fraction of tetrahedral voids is occupied by `Ag^(+)` ionsA. 0.25B. 0.5C. 1D. 0.75 |
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Answer» Correct Answer - B In Agl crystal, number of `Ag^(+)` ions is equal to `I^(-)` ions. However, the number of tetrahedral voids are twice the number of atoms forming the cubic lattice. `therefore` Number of tetrahedral voids occupied by `Ag^(+)` ion =50% |
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| 70. |
Given length of side of hexagonal uint cell is `(100)/sqrt(2)` pm . The volumes of hexagonal unit cell is `("in" "pm"^(3))`:A. `8xx10^(6)`B. `1.5 xx 10^(6)`C. `64 xx 10^(6)`D. `36 xx 10 ^(6)` |
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Answer» Correct Answer - B |
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| 71. |
In ZnS ` , S ^(2-)` ions form ……. Structure while ` Zn^(2+)` ions are present in ……. Voids. |
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Answer» Correct Answer - zinc blende, wurtzite |
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| 72. |
AgI crystallises in a cubic close-packed ZnS structure. What fraction of tetrahedral sites is occupied by `Ag^(+)` ions ? |
| Answer» In the face centred unit cell of AgI, there are four `Ag^(+)` ions and four `I^(-)` ions. As there are four `I^(-)` ions in the packing,therefore there are eight tetrahedral voids. Half of these are occupied by `Ag^(+)` ions. | |
| 73. |
How many effiective `Na^(+)` and `Cl^(-)` ions are present respectively in a uint cell of NaCl solid (Rock salt structure ) if all ions along line connecting opposite face centres are absent ?A. 3,3B. `(7)/(2),4`C. `(7)/(2),(7)/(2)`D. `4,(7)/(2)` |
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Answer» Correct Answer - A |
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| 74. |
Assertion (A) : Frenkel defects are shown by `AgX`. Reason (R ) : `Ag^(o+)` ions have small size.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true bur reason is falseD. If assertion is false bur reason is true |
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Answer» Correct Answer - a Reason is the correct explanation of assertion |
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| 75. |
If a solid `A^(o+)B^(ɵ)` having `ZnS` Structure is heated so that the ions along two of the axis passing throgh the face centre particles are lost and bivalent ion `(Z)` enters herre to maintain the electrical neutrality, so that the new formula unit becomes `A_(x)B_(y)C_(c)`, report the value of `x + y + c`. |
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Answer» Correct Answer - 7 For `ZnS` structure, (`Z_(eff)` of `ZnS = 4`) Number of `B^(ɵ) = 4//"unit cell" ("corner" + "face centre")` Number of `A^(o+) = 4//"unit cell"` (in alternate TVs) Number of `B^(o-)` ion removed `= 4` (Two from each face centre) `xx 1/2` (per face centre share) `= 2` Number of `Br^(ɵ)`ions left `= 4 - 2 = 2//"unit cell"` Number of `Z^(2-)` ions entering in place of `B^(ɵ) = 1`. [To maintain electrical neutrality, `2 B^(ɵ) = 1 Z^(2)`] Formula `= A_(4)B_(2)Z_(`1)` `:. x + y + c = 4 + 2 + 1 = 7` |
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| 76. |
Assertion (A) : In the rock salt type structure, all the `OV_(s)` are occupied by `Na^(o+)` ions. Reason (R ) : Number of `OV_(s) =` Number of `Cl^(ɵ)` ions in the packing.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true bur reason is falseD. If assertion is false bur reason is true |
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Answer» Correct Answer - b Correct explanation `Na^(+)` ions can be placed only in the octabedral (Terahedral viods are ion small to accommodate then) |
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| 77. |
Frenkel defects asre observed where the differnce in size of cation and anion is largeA. The density of crystals having Frenkel defect is less than that of a pure percfect crystalB. In an ionic crystal having Frenkel defect may also contian Schottky defrectC. Usually alkali halides do not Frenkel defectD. Usually alkali halides do not have Frenkel defect |
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Answer» Correct Answer - B |
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| 78. |
Assertion (A): Triclinic system is the most unsymmetrical system. Reason(R): No axial angle is equal to `90^(@)` in triclinic system.A. If both (A) and (R) are correct, and (R) is correct explanation of (A)B. If both (A) and (R) are correct , but (R) is not the correct explanation of (A)C. If (A) is correct , but (R) is incorrect.D. If (A) is correct , but (R) is correct. |
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Answer» Correct Answer - A Assertion is correct. Correct(R): Axial angles are not equal to each other. |
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| 79. |
Assertion (A) : Frenkel defects are shown by `AgX`. Reason (R ) : `Ag^(o+)` ions have small size.A. If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`B. If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`C. If `(A)` is correct, but `(R)` is incorrect.D. If both `(A)` is incorrect but `(R)` is correct. |
| Answer» Correct Answer - A | |
| 80. |
Assertion (A) : In the rock salt type structure, all the `OV_(s)` are occupied by `Na^(o+)` ions. Reason (R ) : Number of `OV_(s) =` Number of `Cl^(ɵ)` ions in the packing.A. If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`B. If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`C. If `(A)` is correct, but `(R)` is incorrect.D. If both `(A)` is incorrect but `(R)` is correct. |
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Answer» Correct Answer - B Correct explanation: `Na^(o+)` ions cen be placed only in `OVs` since `TVs` are too small to accommodate them. |
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| 81. |
In face centred cubic unit cell edge length isA. `(4)/sqrt(3)r`B. `(4)/sqrt(2)r`C. `2r`D. `sqrt(3)/(2)r` |
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Answer» Correct Answer - B In fcc `4r=sqrt(2)arArra=(4r)/sqrt(2)` |
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| 82. |
Assertion (A) : Triclinic systeam is the most unsymmetrical systeam. Reason (R ) : No axial angle is equal to `90^(@)` in triclinic systeam.A. If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`B. If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`C. If `(A)` is correct, but `(R)` is incorrect.D. If both `(A)` is incorrect but `(R)` is correct. |
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Answer» Correct Answer - B Assertion is correct. Correct (R): Axial angels are not equal to each other. |
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| 83. |
The most unsymmetrical system isA. CubicB. HexagonalC. TriclinicD. orthorhombic |
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Answer» Correct Answer - C Triclinic `a != b != c` `alpha != beta != gamma` |
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| 84. |
Schottky defect is likely to be found in :A. AglB. NaClC. ZnSD. ZnO |
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Answer» Correct Answer - B Due to small difference in size of `Na^(+)` and `Cl^(-)` ions and high coordination number, NaCl has schottky defects . |
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| 85. |
Which one of the following is correct ?A. Schottky defect lowers the densityB. Frenkel defect increases the dielectric consstant of the crystalsC. Stoichiometric defects make the crystals good electrical conductorsD. All the three. |
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Answer» Correct Answer - D All the given statements are correct. |
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| 86. |
The volume of atom present in a face-centred cubic unit cell of a metal (`r` is atomic radius ) isA. `(20)/(3) pi r^(3)`B. `(24)/(3)pir^(3)`C. `(12)/(3)pir^(3)`D. `(16)/(3)pir^(3)` |
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Answer» Correct Answer - D Volume of atom in a cell `=(4)/(3)pi r^(3)xxn` `(n=4 fo r f.c.c.)` `=(4)/(3)pi r^(3)xx4=(16)/(3)pi r^(3)` |
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| 87. |
The volume of atom present in a face-centred cubic unit cell of a metal (`r` is atomic radius ) isA. `(20)/(3) pir^(3)`B. `8pir^(3)`C. `4pir^(3)`D. `(16)/(3)pir^(3)` |
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Answer» Correct Answer - D For fcc, `Z_(eff) = 4//"unit cell"` Volume of atoms in the unit cell `= 4/3 pir^(3) xx Z_(eff)` `= 4/3 pi r^(3) xx 4` `= (16)/(3) pir^(3)` |
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| 88. |
Frenkel defect is also known as ……… .A. stoichiometric defectB. dislocation defectC. Impurity defect has no effect on the density of the substanceD. non-stoichiometric defect. |
| Answer» Correct Answer - A::B | |
| 89. |
Which has Frenkel defect ?A. AgBrB. AglC. ZnSD. All of these |
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Answer» Correct Answer - D In Frenkel defect is observed in AgBr, Agl and ZnS. |
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| 90. |
Which of the following unit cells is the most unsymmetrical ?A. TriclinicB. OrthorhombicC. MonoclinicD. Hexagonal |
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Answer» Correct Answer - A Triclinic unit cell is the most unsymmetrical because: `ane b ne c, alpha ne beta ne gamma ne 90^(@)` |
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| 91. |
Al (atomic mass =27) crystallises in a cubic system with edge length (a) equal to `4Å` its density is `2.7 g//cm^(3)` The type of the unit cell is:A. SimpleB. Face centredC. Body centredD. None of these |
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Answer» Correct Answer - B Density `(rho)=(ZxxM)/(N_(0)xxa^(3))` `2.7=(Zxx27)/(6.022xx10^(23)xx(4)^(3)xx(10^(-24)))` On calculation, Z=4 (face centred) |
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| 92. |
The volume of atom present in a face-centred cubic unit cell of a metal (`r` is atomic radius ) isA. `20//3 pir^(3)`B. `24//3 pir^(3)`C. `12//3 pir^(3)`D. `16//3 pir^(3)` |
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Answer» Correct Answer - D Total no. of atoms in fcc unit cell `=4` Total volume `=4xx(4pir^(3))/3=16/3 pir^(3)` |
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| 93. |
Which has Frenkel defect ?A. Sodium chlorideB. GraphiteC. Silver bromideD. Diamond |
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Answer» Correct Answer - C AgBr has Frenkel defect due to large difference in size of `Ag^(+)` and `Br^(-)` ions |
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| 94. |
The number of unit cells in `58.5 g` of `NaCl` is nearlyA. `6xx10^(20)`B. `3xx10^(22)`C. `1.5xx10^(23)`D. `0.5xx10^(24)` |
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Answer» Correct Answer - C `58.5 g (1 "mol")` of NaCl contains `=6.022xx10^(23)` units One unit cell constains 4 NaCl units `:.` No of unit cells present `=(6.022xx10^(23))/4=1.5xx10^(23)` |
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| 95. |
The non- stoichiometric compound `Fe_(0.94)O` is formed when `x%` of `Fe^(2+)` ions are replaced by as many `2//3 Fe^(3+)` ions The value of x is:A. 18B. 12C. 13D. 6 |
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Answer» Correct Answer - A The no. of `Fe^(3+)` ions replacing `xFe^(2+)` ions `=2x//3` `:.` Vacancies of cations `=1-2x//3=x//3` Both `x//3=1-0.94=0.96` `:. X=0.06xx3=0.18 or 18%` |
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| 96. |
To get `n`-type doped semiconductor, impurity to be added to silicon should have the following number of valence electronsA. 2B. 5C. 3D. 1 |
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Answer» Correct Answer - B There should be 5 valence electrons in the impurity atoms |
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| 97. |
To get `n`-type doped semiconductor, impurity to be added to silicon should have the following number of valence electronsA. `1`B. `2`C. `3`D. `5` |
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Answer» Correct Answer - d For n- type , impurity added to sillicon should have more than `4` valence electrons. |
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| 98. |
Assertion : In point defect density of solid maydecrease and increase Reason : Formation `Fe_(0.93) O`is called non-stoichiometric defectA. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true bur reason is falseD. If assertion is false bur reason is true |
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Answer» Correct Answer - b In schottky defect density decreases while interstial defect density increase |
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| 99. |
To get `n`-type doped semiconductor, impurity to be added to silicon should have the following number of valence electronsA. 1B. 2C. 3D. 5 |
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Answer» Correct Answer - D For n-type, impurity added to silicon should have more than 4 valence electrons. |
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| 100. |
In `NaCl`, the chloride ions occuphy the space in a fashion ofA. fccB. bccC. BothD. None |
| Answer» Correct Answer - A | |