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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.
| 801. |
Which of the following defects decrease the density ?A. Interstitial defectB. Vacancy defectC. Frankel defectD. Schottky defect. |
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Answer» Correct Answer - B::D (b,d) Both these defects decrease the density of solids. In both the cases, some lattice sites remain vacant. As a result, the mass decreases but volume does not change. Therefore, density decreases in both the cases. |
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| 802. |
Which of the following defects decrease the density ?A. Intersitital defectB. Vancancy defectC. Frenkel defectD. schottky defect |
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Answer» Correct Answer - C::D In vacancy defect and Schottlk defect, some lattice sites are vacent. Thus, mass decrease but volume remains remains the same. Hence, density decreases. |
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| 803. |
Which of the following defects decrease the density ?A. Intersitital defectB. Vacancey defectC. Frenkel defectD. Sichorttky defect |
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Answer» Correct Answer - B,D In Frenkel and Schottky defect which lead to decrease the density both are the type of a stoichiometric defect. In case of Frenkel defect and intersitial defect, there is no change in density of substance. |
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| 804. |
if the edge length of a NaH unit cell is 488 pm, what is the length of Na-H bond if it crystallises in the fcc structure ?A. 122 pmB. 244 pmC. 488 pmD. 976 pm |
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Answer» Correct Answer - d NaH has fcc structure similar to that of NaCl. ltbr. Thus, edge length of NaH =` 2( r_(Na^(+)) + r_(H^(-)))` i.e, ` 2( r_(Na^(+) + r_(H^(-)) = 488 "pm" ` i.e, ` 2( r_(Na^(+)) + r_(H^(-))) = 488 "pm"` ` r_(Na^(+)) + r_(H^(-)) = 244 "pm"` , which is Na -H bond length. |
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| 805. |
Calculate the distance between (111) planes in a crystal of calcium. Repeat the calculation for (222) planes. Which palnes are closer ? (a = 0.556 nm) |
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Answer» ` d = a/(sqrt(h^(2) +k^(2) +l^(2))` ` d_(111) = 0.556/(sqrt(1^(2) +1^(2) +1^(1))) = 0.556/sqrt12 = 0.161 nm` Thus (222) planes are closer and their distance of separation is half of that of (111) planes. |
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| 806. |
Conductivity of a `"_______"` increase with increase of temperatureA. conductorB. super conductorC. insulatorD. semiconductor |
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Answer» Correct Answer - 4 Intrinsic semiconductors are basically insulators where the energy gap between adjacent energy band is sufficiently small for thermal energy to be able to promote a small number of electrons from the full valence band to the empty conduction band .Both the promoted electrons in the conduction band and the unpaired electrons left in the in the valence band can conduct electricity. The conductivity of semiconductors increase with temperature because the number of electrons promoted to the conduction band increase as temperatures increases. Both n-type and p-type semiconductors bands to the impurity bands or vica versa. A superconductor is a material that loses all electrical resistance below a characteristic temperature called the super conducting transition temperature `T_(C)` Below its `T_(C)` a super conductor becomes a perfect conductor, and an elecrtric current once started flows indefinetly without loss of energy ,for example the electrical resistance of `Hg` falls to zero at its superconducting transiiton temperature `T_(C)=4.2K` Above `T_(C)` mercury is a metallic conductor,Its resistance increases (conductivity decreases) with increasing temperature increase (conductivity decrease) with decreasing temperature .Below `T_(C)` mercury is a superconductor. |
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| 807. |
Which of the following types of semiconductor are used in transistors?A. npn typeB. pnp typeC. pn typeD. Both (1) and (2) |
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Answer» Correct Answer - 4 By combining `p`-type and `n-`type semiconductors we can construct various kinds of transistors devices for controlling electric signals. |
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| 808. |
Which of the following transition metal oxides is like matallic copper in its conducitvity and appearance?A. `ReO_(3)`B. `CrO_(3)`C. `TiO`D. `VO_(3)` |
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Answer» Correct Answer - 1 In the crystal structure of the red coloured `ReO_(3)` oxide,each metal is octahedrally surrounded by `O` atoms.Imagine a cubic unit cell with `Re` atoms at the corners while `O` atoms at the edge centres. |
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| 809. |
Diamagnetic solids are `"________"` By an external magnetic field.A. weakly repelledB. strongly repelledC. weakly attractedD. strongly attracted |
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Answer» Correct Answer - 1 Because their constituent particles do not have any unpaired electrons.The magneitc moment possessed by an electrons with spin in one direction is cancelled by that with spin in the opposite directions. Examples of diamagnetic materials are benzene ,`NaCl` and `TiO_(2)`. |
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| 810. |
Simple cubic structure represented below . Give that there are eight spheres in all , how much space do they take up in the cube ?A. `4 pia^(3)`B. `4pi a^(3)//2`C. `4pi a^(3)//3`D. `4pi a^(3)//8` |
| Answer» Correct Answer - C | |
| 811. |
Simple cubic structure represented below . What is the volume of the entire cube ?A. `2a^(3)`B. `3a^(3)`C. `4a^(3)`D. `8a^(3)` |
| Answer» Correct Answer - D | |
| 812. |
Simple cubic structure represented below . Calculate the percentage of the space in the cube used by the spheres.A. 0.4864B. 0.4854C. 0.5263D. 0.8 |
| Answer» Correct Answer - C | |
| 813. |
The size of the crystals reflect the conditions of growth, rather than the internal constitution of the crystal. NaCl crystals grown at the bottom of a beaker are squre plates whose thickness is never greater than half-their width. Thus the growth rate in either of the two horizontal orientations is twice that in the vertical direction. The appearance of NaCl crystal that are carefully grown by suspending a seed crystal in a slightly uspersaturated solution isA. CubeB. OctahedralC. LinearD. Square |
| Answer» Correct Answer - A | |
| 814. |
The ionic radii of `A^(+) and B^(-)` ions are `0.98 xx 10^(-10) and 1.81 xx 10^(-10) m` .The coordinatyion number of each ion in `AB` isA. `2`B. `6`C. `4`D. `8` |
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Answer» Correct Answer - b `(r_(A+))/(r_(B+)) = (0.98 xx 10^(-10))/( 1.81 xx 10^(-10)) = 0.54` `as (r^(+))/(r^(-)) `is in rabge `414 - 732` so octabedral Co-ordination no of each in `6` like `NaCI` structure |
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| 815. |
The lacttice parameter of `GaAs` (radius of `Ga = 1.22 Å, As = 1.25 Å`) isA. `5.635 Å`B. `2.852 Å`C. `5.774 Å`D. `4.94 Å` |
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Answer» Correct Answer - B `(r_(o+))/(r_(ɵ)) = (i.e., (r_(Ga^(o+)))/(r_(As^(3-)))) = (1.22 Å)/(1.25Å) = 0.976` From radius ratio, it is clear that cation (`Ga^(3+)` ion) lies in body centred or cubic void, where `2(r_(o+) r_(ɵ)) = sqrt(3)a` `2(1.22 + 1.25)Å = sqrt(3)a rArr a = 2.852` |
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| 816. |
In the lattice parameter of `Si = 5.43 Å` and the mass of `Si` atom is `28.08 xx 1.66 xx10^(-27) kg`, the density of silicon in `kg m^(-3)` is (Given: Silicon has diamondcubic structure)A. `2330`B. `1115`C. `3445`D. `1673` |
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Answer» Correct Answer - A `Si` has fcc sturcture `(Z_(eff) = 4` and `Si` is also present in alternate `TVs (= 4)`. So tha total number of atoms `= 4 + 4 = 8//"unit cell"`. `:. rho =m (Z_(eff))/(N_(A) xx a^(3))` [Mas of `Si` atom `= (Aw)(N_(A))`] `= (8 xx "Mass of Si atom")/(a^(3))` `= (8 xx (28.08 xx 1.66 xx 10^(-27))kg)/((5.43 xx 10^(-10))^(3)m^(3)) [1Å = 10^(-10)m]` `= 2330 kg m^(-3)`. |
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| 817. |
The material used in solar cells containsA. `Cs`B. `Si`C. `Sn`D. `Ti` |
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Answer» Correct Answer - B `SiO_(2)` is used in solar cells. |
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| 818. |
The edge length of a face-centred cubic unit cell is `508 pm`. If the radius of the cation is `110 pm` the radius of the anion isA. `144`pmB. `288` pmC. `618` pmD. `398` pm |
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Answer» Correct Answer - A For face-centred cubic unit cell (e.g., that of `NaCl`), edge length `= 2 xx` (Distance between cation and anion `= 2 (r_(c) + r_(a)) = 508 "pm"` (given). Putting `r_(c) = 110 "pm"`, we get `r_(a) = 144 "pm"`. |
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| 819. |
The intermetallic compound `LiAg` crystallizes in cubic lattice in which both lithium and silver have coordination number of `8`. The crystal class isA. Simple cubicB. Body-centred cubicC. Face-centred cubicD. None of these |
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Answer» Correct Answer - B `CN` of `(8:8)` of `Li^(o+)` and `Ag^(o+)` suggest bcc structure. |
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| 820. |
NaCl crystals consist ofA. 0.707:1:1.154B. 1:0.707:1.154C. 1:1:154:0.707D. 0.707:1.154:1 |
| Answer» Correct Answer - 2 | |
| 821. |
The ratio of cations to anion in a octahedral close packing is `:`A. `0.414`B. `0.225`C. `0.02`D. none of these |
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Answer» Correct Answer - a `(r^(+))/(r^(-))` for octahedral void `=0.414,` `(r^(+))/(r^(-))` for cubic`=0.732-1` |
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| 822. |
In the cubic lattice given below, the three distances between the atoms `A-B, A-C`, and `A-G` are, respectively, A. `(a)/(2),(a)/(sqrt(2)),(sqrt(3a))/(2)`B. `a,sqrt(3)a,sqrt(2)a`C. `a,sqrt(2)a,sqrt(3)a`D. `a,(sqrt(3)a)/(2),sqrt(2)a` |
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Answer» Correct Answer - c Edge length `=AB=AD=BC=CD=a` `:. AC=sqrt(AB^(2)+BC^(2))` `=sqrt(a^(2)+a^(2))=sqrt(2)a` `:. AG=sqrt(AC^(2)+CG^(2))` `=sqrt(2a^(2)+a^(2))=sqrt(3)a` |
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| 823. |
If `a` is the length of unit cell, then which one is correct relationship ?A. For simple cubic lattice, Radius of metal atom `=(a)/(2)`B. For `b.c.c.` lattice, Radius of metal atom`=(sqrt(3)a)/(4)`C. For `f.c.c.` lattice, Radius of metal atom `=(a)/(2sqrt(2))`D. All of these |
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Answer» Correct Answer - d These are the formula for radius of metal atom in desired lattice. |
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| 824. |
A solid `A^(+)B^(-)` has NaCl type close packed structure. If the anion has a radius of 250 pm, what should be the ideal radius of cation ? Can a cation ` C^(+)` having a radius of 180 pm be slipped into the tetrahedral site of the crtstal ` A^(+) B^(-) ? Given reason for your answer . |
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Answer» Correct Answer - 173.2 pm `(r_(+)(C^(+)))/(r_(-)(B^(-))) = (180"pm")/(250"pm") = 0.72` It does not ,lie in the range ( 0.225 - 0.414 . Hence `C^(+)` cannot be slipped into the tetrahedral site. |
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| 825. |
The unit cell with the structure below refers to `…………………….` crystal system. A. cubicB. orthorhombicC. tetragonalD. trigonal |
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Answer» Correct Answer - b Note that `:a cancel(=)b cancel(=) c` and `alpha=beta=gamma=90^(@)`, the conditions for orthorhombic system. |
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| 826. |
The C - C and Si - C interatomic distances are 154 pm and 188 pm respectively. The atomic radius of Si isA. 77 pmB. 94 pmC. 114 pmD. 111 pm |
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Answer» Correct Answer - D Atomic radius of Si `=d_(Si-C)-(1)/(2)d_(C-C)=188-(1)/(2)xx154=11` pm |
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| 827. |
Cinnabar is an example of A… crystal system . Here, A refers toA. CubicB. MonoclinicC. TrigonalD. Triclinic |
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Answer» Correct Answer - C Cinnabar is an example of trigonal crystal system |
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| 828. |
If the radius of an atom of an elements is `75` pm and the lattice type is body-centred cubic, what is the edge length of the unit cell?A. `32.475` pmB. `173.2` pmC. `37.5` pmD. `212.1` pm |
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Answer» Correct Answer - B For bcc, `r=(sqrt(3))/(4)a` or `a=(4r)/(sqrt(3))=(4xx75)/(1.732)=173.2` pm |
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| 829. |
When constituent particles are present only on the corner of a unit cell, it is calledA. Primitive unit cellB. Centred unit cellC. Body - centred unit cellD. Face - centred unit cell |
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Answer» Correct Answer - A When constituent particles are present only on the corner of a unit cell , it is called primitive unit cell . |
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| 830. |
Lattice structure of group I elements isA. fccB. bccC. hcpD. ccp |
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Answer» Correct Answer - B The lattice structure of group I element is bcc |
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| 831. |
How many three dimensional lattices are possible ?A. 12B. 13C. 14D. 15 |
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Answer» Correct Answer - C There are only 14 possible three dimesional lattices . These are called bravals lattices |
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| 832. |
Percentages of a free space in cubic close packed structure and in body centered packed structure are respectively.A. 32% and 48%B. 48% and 26%C. 30% and 26%D. 26% and 32% |
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Answer» Correct Answer - C |
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| 833. |
Tetragonal crystal system has the following unit cell dimensions `:`A. `a=b=c=` and `alpha=beta=gamma=90^(@)`B. `a=b ne c` and `alpha=beta=gamma=90^(@)`C. `a ne b ne c` and `alpha=beta=gamma=90^(@)`D. `a=b ne c` and `alpha=beta=90^(@),gamma=120^(@)` |
| Answer» Correct Answer - A | |
| 834. |
Which one of the following is a molecular crystal ?A. Rock saltB. QuartzC. Dry iceD. Diamond |
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Answer» Correct Answer - B |
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| 835. |
The effective number of lattice points per unit cell A. 1B. 2C. 3D. 4 |
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Answer» Correct Answer - C `6xx((1)/(3))+1xx(1)=3`. |
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| 836. |
The number of atoms in a unit cell of a cubic crystal system is 2, the arrangement of atoms is (A) body centred cubicA. octahedralB. fccC. bccD. none of these |
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Answer» Correct Answer - C for bcc, Z = 2 . |
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| 837. |
if a metal has a bcc crystal structure, the coordination number is 8,because `:`A. each atom touches four atoms in the layer above it, four in the layer below it and none in its own layerB. each atom touches four atoms in the layer above it, four in the laayer below it and one in its own layerC. two atoms touch four atoms in the layer above them, four in the layer below them, and none in their own layer.D. each atom touches eight atoms in the layer above it, eight in the layer below it and none in its own layer |
| Answer» Correct Answer - 1 | |
| 838. |
In a ccp structure, the `:`A. first and third layers are repeatedB. first and fourth layers are repeatedC. second and fourth layers are repeatedD. first, third and sixth layers are repeated |
| Answer» Correct Answer - 2 | |
| 839. |
following is the fact about the newly discover superconductor fo `C_(60)` (fullerence).the alkali mental fulleride superconductor `M_(3)C_(60)` has a cubic closesr - packed (face0centered cubic) arrangement of nearly spherical `C_(2-)^(60)` anions with `M^(+)` cations in the holes between the larger `C_(3-)^(60)` ions, the holes are of two types - octahedral hoels , which are surrounded octachedral by six `C_(3-)^(60)` ions. tetarahedral holes , which are surrounded tetrahedrally by for `C_(3-) ^(60)` ions . how many `C_(3-)^(60)` ions , octahedral holes , and tetrachedral holes are prsent pre unit cellA. 5,4,4B. 3,8,4C. 4,4,8D. 2,1,2 |
| Answer» Correct Answer - C | |
| 840. |
The formula for determination of density of unit cell isA. `(a^(3) xx N_(0))/(N xx M) g cm^(-3)`B. `(a^(3) xx M)/(N xx N_(0)) g cm^(-3)`C. `(N xx M)/(a^(3) xx N_(0)) g cm^(-3)`D. `(M xx N)/(a^(3)xx N) g cm^(-3)` |
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Answer» Correct Answer - c Density of unit cell `= (N xx "mol .wt."(M))/(V(= a^(2)) xx "Avogadro no." (N_(0))) g//cm^(-3)` |
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| 841. |
Which of the following type of cubic lattice has maximum number of atoms per unit cell ?A. Simple cubicB. Body centred cubicC. Face centred cubicD. All have same |
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Answer» Correct Answer - C No. of atoms per unit cell are : simple = 1, bcc = 2, fcc = 4. |
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| 842. |
In the distance between `Na^(+)` and `CI^(-)` ions in sodium chliride crystal is X pm , the length of the edge of the unit cell isA. 4a pmB. `(a)/(4)"pm"`C. 2a pmD. `(a)/(2)"pm"` |
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Answer» Correct Answer - C Length of the edge of NaCl unit cell, `=2xx` distance between `Na^(+)` and `Cl^(-)` `=2xxa=2a` pm |
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| 843. |
For Trigonal system, axial rations are `a = b = c ` and the axial angles are kA. `alpha = beta = gamma ne 90^(@)`B. `alpha = beta = gamma = 90^(@)`C. `alpha = gamma = 90^(@), beta ne 90^(@)`D. `alpha ne beta ne gamma ne 90^(@)` |
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Answer» Correct Answer - A For trigonal or Rhombohedral system, `alpha = beta = gamma ne 90^(@)` |
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| 844. |
Diamond belongs to the crystal system :A. cubicB. triclinicC. tetragonalD. hexagonal |
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Answer» Correct Answer - A Diamond belongs to cubic system. |
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| 845. |
Which of the following compound is metallic and ferromagnetic ?A. `CrO_(2)`B. `VO_(2)`C. `MnO_(2)`D. `TiO_(2)` |
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Answer» Correct Answer - b `CrO_(2)` is metallic and ferromagnetic |
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| 846. |
Which of the following exists as covalent crystals in the solid state?A. IodineB. silicon doped with arsennic is a n-type semiconductorC. SulphurD. Phosphorus |
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Answer» Correct Answer - 2 Silicon exists as covalent crystals in the solid state. |
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| 847. |
Which of the following compounds is metallic and ferromagnetic ?A. `TiO_(2)`B. `CrO_(2)`C. `VO_(2)`D. `MnO_(2)` |
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Answer» Correct Answer - 2 `CrO_(2)` is metallic and ferromagnetic |
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| 848. |
What is the number of atoms per unit cell in a body centred cubic structure ? |
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Answer» The number of atoms in a body centred cubic unit cell 1 (At corners ) + 1 (In the body centre )=2. |
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| 849. |
Name the type of defect that occurs in the crystals of zinc sulphide. |
| Answer» Crystals of zinc sulphide (ZnS) suffer from Frenkel defect. | |
| 850. |
STATEMENT -1 : In NaCl structure , ` Na^(+)` ion occupy octahedral holes and `Cl^(-)` ions occupy ccp. STATEMENT -2 : The distance of the nearest neighours in NaCl structure is `a//2` where a is the edge length of the cube .A. If both assertion and reason are correct and reason is correct explanation for assertionB. If both assertion and reason are correct but reason is not correct explanation for assertionC. If assertion is correct but reason is incorrectD. If both assertion and reason are incorrect |
| Answer» Correct Answer - A | |