question_answer 1)
How many unit cells are present in a cube-shaped ideal crystal of \[NaCl\] of mass\[1.00g\]? [Atomic masses:\[Na=23,\text{ }Cl=35.5\]]
A)
\[5.14\times {{10}^{21}}\]unit cells done
clear
B)
\[1.28\times {{10}^{21}}\]unit cells done
clear
C)
\[1.71\times {{10}^{21}}\]unit cells done
clear
D)
\[2.57\times {{10}^{21}}\]unit cells done
clear
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question_answer 2)
In a solid 'AB' having the \[NaCl\]structure, 'A' atoms occupy the corners of the cubic unit cell. If all the face-centered atoms along one of the axes are removed, then the resultant stoichiometry of the solid is
A)
\[A{{B}_{2}}\] done
clear
B)
\[{{A}_{2}}B\] done
clear
C)
\[{{A}_{4}}{{B}_{3}}\] done
clear
D)
\[{{A}_{3}}{{B}_{4}}\] done
clear
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question_answer 3)
Edge length of a cube is 400 pm. Its body diagonal would be
A)
500 pm done
clear
B)
566 pm done
clear
C)
600 pm done
clear
D)
693 pm done
clear
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question_answer 4)
The second order Bragg diffraction of X-rays with \[=1.00\overset{\text{o}}{\mathop{\text{A}}}\,\] from a set of parallel planes in a metal occurs at an angle\[60{}^\circ \]. The distance between the scattering planes in the crystal is
A)
\[0.575\,\overset{\text{o}}{\mathop{\text{A}}}\,\] done
clear
B)
\[1.00\,\overset{\text{o}}{\mathop{\text{A}}}\,\]
done
clear
C)
\[2.00\,\overset{\text{o}}{\mathop{\text{A}}}\,\] done
clear
D)
\[1.15\,\overset{\text{o}}{\mathop{\text{A}}}\,\] done
clear
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question_answer 5)
The radii of \[N{{a}^{+}}\]and \[C{{l}^{-}}\]ions are 95 pm and 181 pm respectively. The edge length of \[NaCl\]unit cell is
A)
276 pm done
clear
B)
138 pm done
clear
C)
552 pm done
clear
D)
415 pm done
clear
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question_answer 6)
\[CsBr\] has bcc structure with edge length 4.3. The shortest interionic distance in between \[C{{s}^{+}}\] and \[B{{r}^{-}}\]is
A)
3.72 done
clear
B)
1.86 done
clear
C)
7.44 done
clear
D)
4.3 done
clear
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question_answer 7)
Potassium crystallizes with a
A)
body-centred cubic lattice done
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B)
face-centred cubic lattice done
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C)
simple cubic lattice done
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D)
orthorhombic lattice done
clear
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question_answer 8)
First three nearest neighbour distances for body centred cubic lattice are respectively:
A)
\[\sqrt{2}a,a,\sqrt{3}a\] done
clear
B)
\[\frac{a}{\sqrt{2}},a,\sqrt{3}a\] done
clear
C)
\[\frac{\sqrt{3}a}{2},a,\sqrt{2}a\] done
clear
D)
\[\frac{\sqrt{3}a}{2},a,\sqrt{3}a\] done
clear
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question_answer 9)
A crystalline solid
A)
changes abruptly from solid to liquid when heated. done
clear
B)
has no definite melting point. done
clear
C)
undergoes deformation of its geometry easily. done
clear
D)
has an irregular 3-dimensional arrangements. done
clear
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question_answer 10)
Which of the following is not a crystalline solid?
A)
\[KCl\] done
clear
B)
\[CsCl\] done
clear
C)
Glass done
clear
D)
Rhombic S done
clear
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question_answer 11)
Which one of the following forms a molecular solid when solidified?
A)
Silicon carbide done
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B)
Calcium fluoride done
clear
C)
Rock salt done
clear
D)
Methane done
clear
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question_answer 12)
The intermetallic compound \[LiAg\] crystallizes in a cubic lattice in which both lithium and silver atoms have coordination number of eight. To what crystal class does the unit cell belong?
A)
Simple cubic done
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B)
Face-centred cubic done
clear
C)
Body-centred cubic done
clear
D)
None of these done
clear
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question_answer 13)
Which set of following characteristics for \[ZnS\] crystal is correct?
A)
Coordination number (4 :4); \[ccp;Z{{n}^{2+}}\]ion in the alternate tetrahedral voids. done
clear
B)
Coordination number (6 : 6); \[hcp;\ Z{{n}^{2+}}\]ion in all tetrahedral voids. done
clear
C)
Coordination number (6 :4); \[hcp;Z{{n}^{2+}}\]ion in all octahedral voids. done
clear
D)
Coordination number (4:4); \[ccp;Z{{n}^{2+}}\]ion in all tetrahedral voids. done
clear
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question_answer 14)
The ionic radii of \[{{X}^{+}}\] and \[{{Y}^{-}}\] ions are 146 and 216 pm respectively. The probable type of structure shown by it is
A)
\[CsCl\] type done
clear
B)
Rock salt type done
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C)
Zinc blende type done
clear
D)
\[Ca{{F}_{2}}\] type done
clear
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question_answer 15)
In \[CsCl\] type structure, the co-ordination number of \[C{{s}^{+}}\] and \[C{{l}^{-}}\] respectively are
A)
6, 6 done
clear
B)
6, 8 done
clear
C)
8, 8 done
clear
D)
8, 6 done
clear
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question_answer 16)
Copper crystallises in fee with a unit length of 361pm. What is the radius of copper atom?
A)
157pm done
clear
B)
128pm done
clear
C)
108pm done
clear
D)
181pm done
clear
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question_answer 17)
In a face centred cubic lattice, atoms of A form the corner points and atoms of B form the face centred points. If two atoms of A are missing from the corner points, the formula of the ionic compound is:
A)
\[A{{B}_{3}}\] done
clear
B)
\[A{{B}_{4}}\] done
clear
C)
\[{{A}_{2}}{{B}_{5}}\] done
clear
D)
\[A{{B}_{2}}\] done
clear
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question_answer 18)
Which one of the following statements about packing in solids is incorrect?
A)
Coordination number in bcc mode of packing is 8. done
clear
B)
Coordination number in hcp mode of packing is 12. done
clear
C)
Void space in hcp mode of packing is 32%. done
clear
D)
Void space is ccp mode of packing is 26%. done
clear
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question_answer 19)
Among the following the incorrect statement is
A)
Density of crystals remains unaffected due to Frenkel defect. done
clear
B)
In BCC unit cell the void space is 32%. done
clear
C)
Density of crystals decreases due to Schottky defect. done
clear
D)
Electrical conductivity of semiconductors and metals increases with increase in temperature. done
clear
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question_answer 20)
In a face centered cubic lattice atoms A are at the comer points and atoms B at the face centered points. If atom B is missing from one of the face centered points, the formula of the ionic compound is:
A)
\[A{{B}_{2}}\] done
clear
B)
\[{{A}_{5}}{{B}_{2}}\] done
clear
C)
\[{{A}_{2}}{{B}_{3}}\] done
clear
D)
\[{{A}_{2}}{{B}_{5}}\] done
clear
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question_answer 21)
A cubic crystal has
A)
thirteen planes of symmetry and nine axis of symmetry. done
clear
B)
thirteen axis of symmetry and nine planes of symmetry. done
clear
C)
thirteen axis and thirteen planes of symmetry. done
clear
D)
nine planes and nine axis of symmetry. done
clear
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question_answer 22)
The appearance of colour in solid alkali meta halides is generally due to:
A)
Schottky defect done
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B)
Frenkel defect done
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C)
Interstitial position done
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D)
F-centres done
clear
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question_answer 23)
A solid AB crystallises as \[NaCl\] structure and the radius of the cation is \[0.100nm.\] The maximum radius of the anion can be:
A)
\[0.137nm\] done
clear
B)
\[0.241nm\] done
clear
C)
\[0.274nm\] done
clear
D)
\[0.482nm\] done
clear
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question_answer 24)
In a monoclinic unit cell, the relation of sides and angles are respectively:
A)
\[a=b\ne c\] and \[\alpha =\beta =\gamma ={{90}^{{}^\circ }}\] done
clear
B)
\[a\ne b\ne c\] and \[\alpha =\beta =\gamma ={{90}^{{}^\circ }}\] done
clear
C)
\[a\ne b\ne c\] and \[\beta =\gamma ={{90}^{{}^\circ }}\ne \alpha \] done
clear
D)
\[a\ne b\ne c\] and \[\alpha \ne \beta \ne \gamma \ne 90{}^\circ \] done
clear
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question_answer 25)
A solid is made of two elements X and Z. The atoms Z are in ccp arrangement while the atoms X occupy all the tetrahedral sites. What is the formula of the compound?
A)
XZ done
clear
B)
\[X{{Z}_{2}}\] done
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C)
\[{{X}_{2}}Z\] done
clear
D)
\[{{X}_{2}}Z{{ }_{3}}\] done
clear
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question_answer 26)
Among the following which is the best description of water in the solid phase?
A)
Covalent solid done
clear
B)
Molecular solid done
clear
C)
Ionic solid done
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D)
Network solid done
clear
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question_answer 27)
\[CsBr\] crystallises in a body centered 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 \[6.02\times {{10}^{23}}mo{{l}^{-1}}\] the density of \[CsBr\] is
A)
\[0.425\text{ }g/c{{m}^{3}}\] done
clear
B)
\[8.5g/c{{m}^{3}}\] done
clear
C)
\[4.25\text{ }g/c{{m}^{3}}\] done
clear
D)
\[82.5\text{ }g/c{{m}^{3}}\] done
clear
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question_answer 28)
Compound that will show the highest lattice energy
A)
KF done
clear
B)
NaF done
clear
C)
CsF done
clear
D)
RbF done
clear
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question_answer 29)
The edge length of unit cell of a metal having molecular weight 75 g/mol is \[5\overset{{}^\circ }{\mathop{A}}\,\] which crystallizes in cubic lattice. If the density is 2g/cc then find the radius of metal atom.\[({{N}_{A}}=6\times {{10}^{23}})\]. Give the answer in pm.
A)
217pm done
clear
B)
210pm done
clear
C)
220pm done
clear
D)
205pm done
clear
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question_answer 30)
Ammonium chloride crystallizes in a body centred cubic lattice with edge length of unit cell of 390 pm. If the size of chloride ion is 180 pm, the size of ammonium ion would be
A)
174 pm done
clear
B)
158 pm done
clear
C)
142 pm done
clear
D)
126 pm done
clear
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question_answer 31)
The cubic unit cell of a metal (molar mass = \[63.55g\text{ }mo{{l}^{-1}}\]) has an edge length of 362 pm. Its density is \[8.92g\text{ }c{{m}^{-3}}.\] The type of unit cell is
A)
primitive done
clear
B)
face centered done
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C)
body centered done
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D)
end centered done
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question_answer 32)
A solid has a 'bcc' structure. If the distance of nearest approach between two atoms is \[1.73\overset{{}^\circ }{\mathop{A}}\,\], the edge length of the cell is
A)
314.20 pm done
clear
B)
1.41 pm done
clear
C)
200 pm done
clear
D)
216 pm done
clear
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question_answer 33)
When molten zinc is converted into solid state, it acquires hcp structure. The number of nearest neighbours of Zn will be
A)
6 done
clear
B)
12 done
clear
C)
8 done
clear
D)
4 done
clear
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question_answer 34)
The radius of a calcium ion is 94 pm and of the oxide ion is 146 pm. The possible crystal structure of calcium oxide will be
A)
tetrahedral done
clear
B)
trigonal done
clear
C)
octahedral done
clear
D)
pyramidal done
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question_answer 35)
An alloy of copper, silver and gold is found to have cubic lattice in which Cu atoms constitute ccp. If Ag atoms are located at the edge centres and Au atom is present at body centre, the alloy will have the formula
A)
\[CuAgAu\] done
clear
B)
\[C{{u}_{4}}A{{g}_{4}}Au\] done
clear
C)
\[C{{u}_{4}}A{{g}_{3}}Au\] done
clear
D)
\[C{{u}_{4}}A{{g}_{6}}Au\] done
clear
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question_answer 36)
A solid has a structure in which 'W' atoms are located at the comers of a cubic lattice 'O' atoms at the centre of edges and Na atoms at the centre of the cube. The formula for the compound is
A)
\[N{{a}_{2}}W{{O}_{3}}\] done
clear
B)
\[N{{a}_{2}}W{{O}_{2}}\] done
clear
C)
\[NaW{{O}_{2}}\] done
clear
D)
\[NaW{{O}_{3}}\] done
clear
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question_answer 37)
If calcium crystallizes in bcc arrangement and the radius of Ca atom is 96 pm, then the volume of unit cell of Ca is
A)
\[10.9\times {{10}^{-36}}{{m}^{3}}\] done
clear
B)
\[10.9\times {{10}^{-30}}{{m}^{3}}\] done
clear
C)
\[21.8\times {{10}^{-30}}{{m}^{3}}\] done
clear
D)
\[21.8\times {{10}^{-36}}{{m}^{3}}\] done
clear
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question_answer 38)
How many unit cells are present in 5.0 gm of crystal AB (formula mass of AB = 40) having rock salt type structure? (\[{{N}_{A}}\]= Avogadro's no.)
A)
\[{{N}_{A}}\] done
clear
B)
\[\frac{{{N}_{A}}}{10}\] done
clear
C)
\[4{{N}_{A}}\] done
clear
D)
none of these done
clear
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question_answer 39)
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 done
clear
B)
250 pm done
clear
C)
200 pm done
clear
D)
300 pm done
clear
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question_answer 40)
The number of unit cells in 58.8 g of \[NaCl\] is nearly
A)
\[6\times {{10}^{20}}\] done
clear
B)
\[3\times {{10}^{22}}\] done
clear
C)
\[1.5\times {{10}^{23}}\] done
clear
D)
\[0.5\times {{10}^{24}}\] done
clear
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question_answer 41)
An element having an atomic radius of 0.14 nm crystallizes in an fcc unit cell. What is the length of a side of the cell?
A)
\[0.56\text{ }nm\] done
clear
B)
\[0.24\text{ }nm\] done
clear
C)
\[0.96\text{ }nm\] done
clear
D)
\[0.4nm\] done
clear
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question_answer 42)
Which of the following has maximum value of cation/ anion ratio?
A)
\[KCl\] done
clear
B)
\[NaCl\] done
clear
C)
\[Ca{{F}_{2}}\] done
clear
D)
\[MgC{{l}_{2}}\] done
clear
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question_answer 43)
Which of the following statements is correct for ionic solids?
A)
Ionic solids are soluble in \[CC{{l}_{4}},{{C}_{6}}{{H}_{6}}\], etc. done
clear
B)
Under the electric field cations and anions acquire translatory motion in opposite directions. done
clear
C)
Structural units have strong electrostatic force of attraction. done
clear
D)
Structural units have dipole-dipole interactions. done
clear
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question_answer 44)
Total volume of atoms present in a face-centred cubic unit cell of a metal is (r is atomic radius)
A)
\[\frac{12}{3}\pi {{r}^{3}}\] done
clear
B)
\[\frac{16}{3}\pi {{r}^{3}}\] done
clear
C)
\[\frac{20}{3}\pi {{r}^{3}}\] done
clear
D)
\[\frac{24}{3}\pi {{r}^{3}}\] done
clear
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question_answer 45)
An element occurring in the bcc structure has \[12.08\times {{10}^{23}}\]unit cells. The total number of atoms of the element in these cells will be
A)
\[24.16\times {{10}^{23}}\] done
clear
B)
\[36.18\times {{10}^{23}}\] done
clear
C)
\[6.04\times {{10}^{23}}\] done
clear
D)
\[12.08\times {{10}^{23}}\] done
clear
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question_answer 46)
In an antifluorite structure, cations occupy
A)
octahedral voids done
clear
B)
centre of cube done
clear
C)
tetrahedral voids done
clear
D)
corners of cube done
clear
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question_answer 47)
The number of atoms in 100 g of an fcc crystal with density, \[d=10g/c{{m}^{3}}\] and cell edge equal to 100 pm, is equal to
A)
\[1\times {{10}^{25}}\] done
clear
B)
\[2\times {{10}^{25}}\] done
clear
C)
\[3\times {{10}^{25}}\] done
clear
D)
\[4\times {{10}^{25}}\] done
clear
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question_answer 48)
Crystal defect indicated m the diagram below is
\[N{{a}^{+}}C{{l}^{-}}N{{a}^{+}}C{{l}^{-}}N{{a}^{+}}C{{l}^{-}}\]
\[C{{l}^{-}}[\,\,\,\,]\,C{{l}^{-}}N{{a}^{+}}\,[\,\,\,\,]\,N{{a}^{+}}\]
\[N{{a}^{+}}C{{l}^{-}}\,[\,\,\,\,]\,C{{l}^{-}}N{{a}^{+}}C{{l}^{-}}\]
\[C{{l}^{-}}N{{a}^{+}}C{{l}^{-}}N{{a}^{+}}\,[\,\,\,\,]\,N{{a}^{+}}\]
A)
Interstitial defect done
clear
B)
Schottky defect done
clear
C)
Frenkel defect done
clear
D)
Frenkel and Schottky defects done
clear
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question_answer 49)
In the laboratory, sodium chloride is made by burning sodium in the atmosphere of chlorine. The salt obtained is yellow in colour. The cause of yellow colour is:
A)
Presence of \[N{{a}^{+}}\] ions in the crystal lattice done
clear
B)
Presence of \[C{{l}^{-}}\] ions in the crystal lattice done
clear
C)
Presence of electrons in the crystal lattice done
clear
D)
Presence of face centred cubic crystal lattice. done
clear
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question_answer 50)
Each of the following solids show, the Frenkel defect except
A)
\[ZnS\] done
clear
B)
\[AgBr\] done
clear
C)
\[AgI\] done
clear
D)
\[KCl\] done
clear
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question_answer 51)
Schottky defect in crystals is observed when
A)
an ion leaves its normal site and occupies an interstitial site. done
clear
B)
unequal number of cations and anions are missing from the lattice. done
clear
C)
density of the crystal increases. done
clear
D)
equal number of cations and anions are missing from the lattice. done
clear
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question_answer 52)
In the solid state, MgO has the same structure as that of sodium chloride. The number of oxygens surrounding each magnesium in MgO is
A)
6 done
clear
B)
1 done
clear
C)
2 done
clear
D)
4 done
clear
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question_answer 53)
Which is incorrect statement?
A)
In \[NaCl\] structure, tetrahedral voids are unoccupied. done
clear
B)
In \[ZnS\] structure, octahedral voids are unoccupied. done
clear
C)
In \[Ca{{F}_{2}}\] structure, all tetrahedral voids are occupied. done
clear
D)
In \[N{{a}_{2}}O\] structure, all tetrahedral voids are unoccupied. done
clear
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question_answer 54)
The \[{{r}_{+}}/{{r}_{-}}\] ratio of \[ZnS\] is 0.402. Pick out the incorrect statements from the following?
A)
\[ZnS\] is 4:4 coordination compound. done
clear
B)
\[ZnS\] does not crystallize in rock salt type lattice because \[{{r}_{+}}/{{r}_{-}}\] is too small to avoid overlapping of \[{{S}^{2-}}\] ions. done
clear
C)
\[Z{{n}^{2+}}\] ion is too small to fit precisely into the octahedral voids of \[{{S}^{2-}}\] ions. done
clear
D)
\[Z{{n}^{2+}}\] ion is too large to fit into the octahedral voids of \[{{S}^{2-}}\] ions. done
clear
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question_answer 55)
For fcc, if AB is just like the rock salt like structure then, \[{{A}^{+}}\] and \[{{B}^{-}}\] are located at -
A)
\[{{A}^{+}}\]- Tetrahedral voids ; \[{{B}^{-}}\]- Corner done
clear
B)
\[{{A}^{+}}\] - Corner and faces; \[{{B}^{-}}\] - Octahedral voids done
clear
C)
\[{{A}^{+}}\] - Octahedral voids; \[{{B}^{-}}\]- Corner and faces done
clear
D)
\[{{A}^{+}}\] - Corner and faces; \[{{B}^{-}}\] - Octahedral and tetrahedral voids done
clear
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question_answer 56)
A metal has fcc lattice. The edge length of the unit cell is 404 pm. The density of the metal is \[2.72\text{ }g\text{ }c{{m}^{-3}}.\] The molar mass of the metal is: (\[{{N}_{A}}\] Avogadro's constant \[=6.02\times {{10}^{23}}mo{{l}^{-1}}\])
A)
\[30g \text{ }mo{{l}^{-1}}\] done
clear
B)
\[27g mo{{l}^{-1}}\] done
clear
C)
\[20g mo{{l}^{-1}}\] done
clear
D)
\[40g mo{{l}^{-1}}\] done
clear
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question_answer 57)
What is the energy gap between valence band and conduction band in crystal of insulators?
A)
Both the bands are overlapped with each other done
clear
B)
Very small done
clear
C)
Infinite done
clear
D)
Very large done
clear
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question_answer 58)
The addition of arsenic to germanium makes the latter a
A)
metallic conductor done
clear
B)
intrinsic semiconductor done
clear
C)
mixed conductor done
clear
D)
extrinsic semiconductor done
clear
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question_answer 59)
A mineral having the formula \[A{{B}_{2}}\] crystallizes in ccp lattice with A atoms occupying the lattice points. Pick out the correct statement of the following
A)
100% occupancy of tetrahedral voids, C.N. of \[B=4\] done
clear
B)
100% occupancy of octahedral voids, C.N. of B=4 done
clear
C)
50% occupancy of tetrahedral voids, C.N. of A=4 done
clear
D)
100% occupancy of octahedral voids, C.N. of A =4 done
clear
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question_answer 60)
Superconductors are derived from compounds of
A)
p-block elements done
clear
B)
lanthanides done
clear
C)
actinides done
clear
D)
transition elements done
clear
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question_answer 61)
If \[NaCl\] is doped with \[{{10}^{-4}}mol\text{ }%\] of \[SrC{{l}_{2}}\], the concentration of cation vacancies will be \[({{N}_{A}}=6.02\times {{10}^{23}}mo{{l}^{-1}})\]
A)
\[6.02\times {{10}^{16}}mo{{l}^{-1}}\] done
clear
B)
\[6.02\times {{10}^{17}}mo{{l}^{-1}}\] done
clear
C)
\[6.02\times {{10}^{14}}mo{{l}^{-1}}\] done
clear
D)
\[6.02\times {{10}^{15}}mo{{l}^{-1}}\] done
clear
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question_answer 62)
Predict coordination number of the cation in crystals of the following compounds:
1. \[MgO:{{r}_{c}}=0.65\overset{\text{o}}{\mathop{\text{A}}}\,\,;\,\,{{r}_{a}}=1.40\overset{\text{o}}{\mathop{\text{A}}}\,,\]
2. \[MgS:{{r}_{c}}=0.65\overset{\text{o}}{\mathop{\text{A}}}\,\,;\,{{r}_{a}}=1.84\overset{\text{o}}{\mathop{\text{A}}}\,,\]
A)
6, 4 done
clear
B)
4, 6 done
clear
C)
3, 4 done
clear
D)
6, 8 done
clear
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question_answer 63)
An element (atomic mass\[=100\text{ }g/mol\]) having bcc structure has unit cell edge 400 pm. Then, density of the element is
A)
\[10.376g/c{{m}^{3}}\] done
clear
B)
\[5.188g/c{{m}^{3}}\] done
clear
C)
\[7.289\text{ }g/c{{m}^{3}}\] done
clear
D)
\[2.144g/c{{m}^{36}}\] done
clear
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question_answer 64)
\[MgO\] crystallizes in a cubic type crystal system. The ionic radii for \[M{{g}^{2+}}\] and \[{{O}^{2-}}\] are 0.066 and 0.140 nm respectively. One can conclude that the \[M{{g}^{2+}}\] ions occupy
A)
a cubic hole in a simple cubic structure. done
clear
B)
every tetrahedral hole in a close packed structure. done
clear
C)
an octahedral hole in a cubic close packed structure. done
clear
D)
every other tetrahedral hole in a close packed structure. done
clear
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question_answer 65)
A crystal lattice with alternate positive and negative ions has radius ratio 0.524. Its co-ordination number is
A)
4 done
clear
B)
3 done
clear
C)
6 done
clear
D)
12 done
clear
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question_answer 66)
The correct statement regarding F- centre is
A)
electrons are held in the voids of crystals. done
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B)
F - centre produces colour to the crystals. done
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C)
conductivity of the crystal increases due to F - centre. done
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D)
All of these done
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question_answer 67)
The number of octahedral void(s) per atom present in a cubic close-packed structure is
A)
1 done
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B)
3 done
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C)
2 done
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D)
4 done
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question_answer 68)
If we mix a pentavalent impurity in a crystal lattice of germanium, what type of semiconductor formation will occur?
A)
p-type done
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B)
n-type done
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C)
Both [a] and [b] done
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D)
Neither [a] nor [b] done
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question_answer 69)
A \[NaCl\] crystal is changed into \[CsCl\] type structure by:
A)
Increasing temperature and decreasing pressure. done
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B)
Increasing pressure and decreasing temperature. done
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C)
Increasing both temperature and pressure done
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D)
None of these. done
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question_answer 70)
To get a n-type semiconductor, the impurity to be added to silicon should have which of the following number of valence electrons
A)
1 done
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B)
2 done
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C)
3 done
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D)
5 done
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question_answer 71)
The empty space in the body centred cubic lattice is
A)
68% done
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B)
52.4% done
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C)
47.6% done
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D)
32% done
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question_answer 72)
A solid with high electrical and thermal conductivity is
A)
Si done
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B)
Li done
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C)
\[NaCl\] done
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D)
Ice done
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question_answer 73)
How many effective \[N{{a}^{+}}\] and \[C{{l}^{-}}\] ions are present respectively in a unit cell of \[NaCl\] solid (Rock salt structure) if all ions along line connecting opposite face centres are absent?
A)
3, 3 done
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B)
\[\frac{7}{2},4\] done
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C)
\[\frac{7}{2},\frac{7}{2}\] done
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D)
\[4,\frac{7}{2}\] done
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question_answer 74)
In a normal spinel type structure, the oxide ions are arranged in ccp whereas 1/8 tetrahedral holes are occupied by \[Z{{n}^{2+}}\] ions and 50% of octahedral holes are occupied by \[F{{e}^{3+}}\] ions .The formula of the compound is
A)
\[Z{{n}_{2}}F{{e}_{2}}{{O}_{4}}\] done
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B)
\[ZnF{{e}_{2}}{{O}_{3}}\] done
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C)
\[ZnF{{e}_{2}}{{O}_{4}}\] done
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D)
\[ZnF{{e}_{2}}{{O}_{2}}\] done
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question_answer 75)
Non stoichiometric defects are formed by
A)
s-block elements done
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B)
p-block elements done
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C)
either s-block elements or d-block elements done
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D)
only d-block elements. done
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question_answer 76)
Which of the following metal oxides is anti- ferromagnetic in nature?
A)
\[Mn{{O}_{2}}\] done
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B)
\[Ti{{O}_{2}}\] done
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C)
\[V{{O}_{2}}\] done
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D)
\[Cr{{O}_{2}}\] done
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question_answer 77)
A molecule \[{{A}_{2}}B\](Mwt. = 166.4) occupies triclinic lattice with a \[5\overset{\text{o}}{\mathop{\text{A}}}\,,\text{ }b=8\overset{\text{o}}{\mathop{\text{A}}}\,,\] and \[c=4\overset{\text{o}}{\mathop{\text{A}}}\,.\] If the density of \[A{{B}_{2}}\] is\[5.2\text{ }g\text{ }c{{m}^{-3}}\], the number of molecules present in one unit cell is
A)
2 done
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B)
3 done
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C)
4 done
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D)
5 done
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question_answer 78)
Doping of silicon (Si) with boron leads to:
A)
n-type semiconductor done
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B)
p-type semiconductor done
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C)
Metal done
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D)
Insulator done
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question_answer 79)
Non-stoichiometric compound have the properties of:
A)
Electrical conductance done
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B)
Isolation done
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C)
Insulation done
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D)
None of these done
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question_answer 80)
Which one of the following statements is correct?
A)
\[NaCl\] is a paramagnetic salt done
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B)
\[CuS{{O}_{4}}\] is a diamagnetic salt done
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C)
\[MnO\] is an example of ferromagnetic substance done
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D)
Ferrimagnetic substance like \[ZnF{{e}_{2}}{{O}_{4}}\] becomes paramagnetic on heating done
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