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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.
| 401. |
Why Frenkel defects are not found in pure alkali metal halides? |
| Answer» The Frenkel defect is not shown by alkali metal halides because the size of the cation is too big to be accommodated in the interstitial space. Therefore, the cation does not leave its normal position in the lattice. | |
| 402. |
Due to crystal fractures , the slippage of the planes relative to each other is the easiest way of distorting the crystal . However,even along their most favoured direction distortion of the crystals required a large force it is due toA. displacement may bring ions of the same charge close to each other .B. displacement may bring ions of the same charge away to each other .C. coulombic forcesD. motion of these planes in a direction parallel to these rows of ions. |
| Answer» Correct Answer - C | |
| 403. |
Following frightening diagrams show identical cubes such that edge of cube 2 lies exactly in the middle of one of the faces of Cube 1 and Cube 4 has a corner at the body centre of the cube 3 . Find the contribution (in fraction) of the spheres shown to each of the cube 1 ,2 , 3 and 4 respectively is A. `(1)/(2) , (1)/(4) , 1 , (1)/(8)`B. `(1)/(2) , (1)/(4) , (1)/(8) , 1`C. `(1)/(8) , (1)/(4) , 1 , (1)/(2)`D. `(1)/(8) , (1)/(4), (1)/(2) , 1` |
| Answer» Correct Answer - A | |
| 404. |
In a solid between A and B atoms of A are arranged in ccp array and atoms of B occupy all the octahedral voids and half of the tetrahedral voids. The formula of the compound isA. `A_(2)B`B. `A_(3)B_(4)`C. `AB_(2)`D. `AB_(3)` |
| Answer» For every atom of A, there are one octahedral hole and two tetrahedral holes | |
| 405. |
In an ideal crystal, the entropy of the constituents at absolute zero temperature (0K) is zero. However, the crystals generally suffer from certain defects also called imperfections They may be both electronic and atomic in nature. The atomic imperfections may be stoichiometric (Schottky and Frenkel defects) or non-stoichiometric (metal excees and metal deficiency defects). In addition to these, there are impurity defects which are caused by the addition of certain impurities of metals and this is known as dopping. The dopping leads to semi conductors which may be either n-type or p-type in nature. Which of the following is correct ?A. Schottky defect lowers the density of crystalsB. Frenkel defect increases the dielectric constant of crystalsC. Stoichiometric defects make crystals good conductors of electricityD. All the three are correct |
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Answer» Correct Answer - D All statements are correct |
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| 406. |
In an ideal crystal, the entropy of the constituents at absolute zero temperature (0K) is zero. However, the crystals generally suffer from certain defects also called imperfections They may be both electronic and atomic in nature. The atomic imperfections may be stoichiometric (Schottky and Frenkel defects) or non-stoichiometric (metal excees and metal deficiency defects). In addition to these, there are impurity defects which are caused by the addition of certain impurities of metals and this is known as dopping. The dopping leads to semi conductors which may be either n-type or p-type in nature. Zinc oxide (ZnO) is white when cold and yellow when hot. It is due to the development of :A. Frenkel defectB. Schottky defectC. Metal excees defectD. Metal deficiency defect |
| Answer» Correct Answer - C | |
| 407. |
Wax is an example ofA. ionic crystalB. covalentC. molecular crystalD. amorphous solid |
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Answer» Correct Answer - C |
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| 408. |
Wax is an example ofA. Ionic crystalB. Covalent crystalC. Molecular crystalD. Metallic crystal. |
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Answer» Correct Answer - C Wax is a molecular crystal. |
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| 409. |
An ionic compound has a unit cell consisting of A ions at the corners of a cube and B ions on the centers of the faces of the cube .The empirical formula for this compound would beA. ABB. `A_(2)B`C. `AB_(3)`D. `A_(3)B` |
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Answer» Correct Answer - C A ions are at eight corners of the cube. Therefore the no. of A ions in the unit cell `=(8)/(8)=1.` B ions are at the face centre of six faces. Therefore, its share in the unit cell `=(6)/(2)=3` . The formula is `AB_(3)` . |
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| 410. |
Statement 1: Diamond and graphite do not have the same crystal structure. Statement 2: Diamond is crystalline while graphite is amorphous.A. Statement 1 is true, statement 2 is true: statement 2 is a correct explanation for statement 1.B. Statement 1 is true, statement 2 is true, statement 2 is nota correct explanation for statement 1C. Statement 1 is true, statement 2 is falseD. Statement 1 is false, statement 2 is true. |
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Answer» Correct Answer - C In diamond C-atoms are `sp^(3)` hybridized while in graphite, they are `sp^(2)` hybridized. |
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| 411. |
Given : `{:(,"Column A","Column B"),((A),"Ionic solid",(I)NaCl),((B),"Metallic solid",(II) Fe),((C),"Covalent solid",(III)C("graphite")),((D),"Molecular solid",(IV)"Dry ice"):}`A. A - II, B - I, C - IV, D - IIIB. A - I, B - II, C - III, - D - IVC. A - III, B - II, C - I, D - IVD. A - II, B - IV, C - I, D - III21. |
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Answer» Correct Answer - B It is a fact. |
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| 412. |
In graphite, electrons areA. Iocalised on each carbon atomB. spread out between third carbon atomC. localised on every third carbon atomD. present in antibonding orbital. |
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Answer» Correct Answer - D In graphite, the electrons are spread out between the sheets. |
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| 413. |
Graphite is a soft lubricent extremely difficuit to melt .The reason for this anomalous behaviour is that graphitsA. is a non-crystalline substnaceB. is n non-allotropic form of diamondC. has molecules of variable molecular masses like polymersD. has carbon atoms arranged in large plate of ring of stongly bound carbon atoms with weak interplate bonds |
| Answer» Correct Answer - d | |
| 414. |
In graphite adjacent layers of carbon atoms are held together byA. coordinate covalent bondB. covalent bondsC. van der Waals forcesD. double bonds. |
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Answer» Correct Answer - C Layers of carbon atoms in graphite are held together by van der Weels forces. |
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| 415. |
With respect to graphite and diamond, which of the statement given is correct?A. Graphite is harder than diamondB. Graphite has higher electrical conductivity than diamondC. Graphite has higher thermal conductivity than diamondD. Graphite has smaller C - C bond order than diamond |
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Answer» Correct Answer - B (a) Diamond is harder than graphite. Hence (a) is incorrect. (b) Graphite is a good conductor of electricity at eacj C-atom is attached to three other C-atoms and 4th electron is free while in diamond, all the four valenies are satisfied and hence, it is insulator. Thus (b) is correct. (c) Diamond, is better thermal conductor than graphite . This is because thermal conduction is due to transfer of thermal vibrations from atom to atom which is easier in a compact crystal like that of diamond. Hence, (c) is incorrect. (d) In graphite, C-C bond acquires some double bond character. Hence, it has higher bond order than diamond . Thus (d) is incorrect. |
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| 416. |
In graphite, electrons areA. localised on each carbon atomB. spread out between the sheetsC. localised on every third carbon atomD. present in antibonding orbital |
| Answer» Correct Answer - 2 | |
| 417. |
Graphite belongs toA. cubic systemB. Tetragonal systemC. rhombohedral systemD. Hexoagonal system |
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Answer» Correct Answer - D Graphite belongs to hexagonal system. |
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| 418. |
Platinum crystallises in a face centered cube crystal with a unit cell length of 3,9231 `Å`. The density and atomic radius of platinum are respectively. [Atomic mass of Pt = 195]A. `45.25g. cm^(-3), 2.516Å`B. `21.86 g. cm^(-3), 1.387Å`C. `29.46g.cm^(-3), 1.48Å`D. None of these |
| Answer» Correct Answer - B | |
| 419. |
Urea has a sharp melting point but glass does not. Explain. |
| Answer» Urea is a crystalline molecular solid and it has a sharp melting point. On the other hand, glass is an amorphous solid and its melting point is not sharp. | |
| 420. |
The coordination number of cation and anion in fluorite `CaF_(2)` and anti-fluroite `Na_(2)O` are respectively:A. 8:4 and 6:3B. 6:3 and 4:4C. 8:4 and 4:8D. 4:8 and 8:4 |
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Answer» Correct Answer - C |
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| 421. |
In terms of intermolecular forces, explain why do some substances exist as solids ? |
| Answer» When the constituent particles of a substance are so closely packing that the intermolecular forces of attraction are much stronges than the thermal energy, the substance exists as a solid. | |
| 422. |
The ionic radii of `Rb^(+)` and `I^(-)` are 1.46 and `2.16Å`. The most probable type of structure exhibited by it is:A. CsCl typeB. ZnS typeC. NaCl typeD. `CaF_(2)` type. |
| Answer» Correct Answer - D | |
| 423. |
The ionic radii of `Rb^(+)` and `I^(-)` are 1.46 and `2.16Å`. The most probable type of structure exhibited by it is:A. CsCl typeB. ZnS typeC. NaCl typeD. `CaF_2` type |
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Answer» Correct Answer - C According to radius ratio rule, `(r_(c^+)(Rb^+))/(r_(a)(I^-)) = (1.46)/(2.16) = 0.676` It will have coordination number 6 and structure will be same as of NaCl |
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| 424. |
under the influence of electric field , which of the following statement is true about the movement of electrons and holes in p- type semiconducter ?A. Electron will move towards the positively charged plate through electron holesB. Holes will appear to be moving towards the negatively chared plateC. both electrons and holes appear to move towards the positively charged plateD. Movement of elecrons Is not reated to the movement of holes |
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Answer» Correct Answer - A,B in p - type semicondutor the conductivity is due to existence of hole , when electric field is applied to p- type semiconductor hole starts moving towards negatively charged charged plate and electron otwards positvely charged plate . |
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| 425. |
which of the following statements are true about semiconductor ?A. silicon doped with electron rich impurity is a type semiconductorB. Silicon doped with an electrons rich impuriy is an n-type semipucoterC. Delocalised electrons increase the conductivity of doped siliconD. An electron vacancy incease the conductivity of n- type semiconductor |
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Answer» Correct Answer - B,C silicon soped with an electron rich ompurity is an n-type semiconductor , Condcity of n- type semiconductor is due to presence of free electron delocalisation of electrons increase the conductivity of deped silicon due to increase in mobility of electron. |
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| 426. |
In face -centered cubic unit cell, edge length isA. a//2B. `a//sqrt(2)`C. `a//2 sqrt(2)`D. ` 3sqrt(2)//4` |
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Answer» Correct Answer - C |
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| 427. |
Consider a cube 1 of Body Centered Cubic unit cell of edge length a now atom at the body center can be viewed to be lying on the corner of another cube2. Find the volume common to cube 1 and cube 2A. `(a^(3))/(27)`B. `(a^(3))/(64)`C. `(a^(3))/(2sqrt2)`D. `(a^(3))/(8)` |
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Answer» Correct Answer - D Common volume `= ((a)/(2))^(3) = (a^(3))/(8)` [`:.` common vol is a cube of edge length `(a)/(2)`] |
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| 428. |
Salt AB has a zinc blende structre. The radius of `A^(2+)` and `B^(2-)` ion are `0.7Å and 0.Å` respectively. The edge length of AB unit cell is:A. `2.5Å`B. `5.09Å`C. `5 Å`D. `5.77Å` |
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Answer» Correct Answer - D |
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| 429. |
Transition metals, when they form interestitial compounds, the non-metals (H,B,C,N) ar accodated in:A. voids or holes in cubic-packed structureB. tetrahedral voidsC. octahedral voidsD. all of these |
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Answer» Correct Answer - D |
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| 430. |
The density of solid argon is 1.65 ` " g mL"^(-1) at - 233^(@)C` . If the argon atom is assumed to be sphere of radius ` 1.54 xx 10^(-8)` cm. What precentage of solid argon is apparaently empty space ? (At . Mass of Ar = 40) |
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Answer» density of ` 1.65 " g mL" ^(-1)` means that 1.65 g of solid argon has volume =1 mL Volume of one atom of Ar =` 4/3 pi r^(3)` No. Of atoms in 1.65 g or 1 mL of solid `Ar = ((1.65)/40 "mol") (6.023 xx10^(23) "mol"^(-1)) = ( 1.65xx6.023xx10^(23))/40` Total volume of all atoms Ar in 1 mL of Ar. `4/3 pi r^(3)xx(1.65xx6.023xx10^(23))/40` =` 4/3xx22/7 xx(1.54 xx10^(-8))^(3) xx (1.65xx6.023xx10^(23))/40 ` 0.380 ` cm^(3) or` 0.380 mL. Empty space = (1 -0.380) mL= 0.620 mL % empty spae =` ( 0.620)/ 1 xx 100 = 62 %` |
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| 431. |
In which pair most efficient packing is present ?A. hcp and bccB. hcp and ccpC. bcc and ccpD. bcc and simple cubic cell |
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Answer» Correct Answer - C In hcp and ccp, space occupied = 74 % while in bcc, it is 68% . |
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| 432. |
In which pair most efficient packing is present?A. bcp and bccB. hcp and ccpC. bcc and ccpD. bcc and simple cubic cell |
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Answer» Correct Answer - B Packing efficiency for hcp or ccp is calculated to be 74% which is maximum among all type of crystals. |
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| 433. |
There is a collection of crystalline substances in a hexagonal close packing. If the density of matter is ` 2.6 g//cm^(3)`, what would be the average density of matter in colleciton ? What fractionofthe space is actually unoccupied ? |
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Answer» In hexagonal close packing, packing efficiency is 74 % Density of matter = Packing fraction ` xx ` Total density = ` 74/100 xx 2.6 = 1.924 " g/cm"^(3)` % empty space ( space unoccupied ) = 100 - 74 = 26% . |
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| 434. |
Most of the ferrites have …… structure. |
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Answer» Correct Answer - `MgAl_(2) O_(4)` |
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| 435. |
A compound formed by elements A and B crystallizes in cubic structure where A atoms are at the corners of a cube and B atoms are at the face center . What is the formula of the compound ?A. ABB. `AB_(2) `C. `AB_(3)`D. `A_(2)B_(3)` |
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Answer» Correct Answer - C A atom are eight corners of the cube. therefore , the number of A atoms in the unit cell B atoms are at the face centere of six faces Therefore, its share in the unit cell. |
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| 436. |
A compound formed by elements `A` and `B` crystallizes in cubic structure, where `A` atoms are at the corners of a cube and `B` atoms are at the face `-` centre. What is the formula of the compound ? |
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Answer» Correct Answer - `AB_(3);` |
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| 437. |
The correct order to the packing efficiency in different types of unit cells is ….A. fcc lt bcc lt simple cubicB. fcc gt bcc gt simple cubicC. fcc lt bcc gt simple cubicD. bcc lt fcc gt simple cubic |
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Answer» Correct Answer - A Fcc = 0.74 , bcc = 0.68 , simple = 0.524 , Hence, fcc gt bcc gt simple. |
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| 438. |
The coordinate of the three corners of a shaded face on a cubic unit cell are ` (1/2 , 1/2 ,1) , ( 0,1, 1/2) and ( 1,1, 1/2)` as shown in the figure. Determine the Miller indices of the plane. |
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Answer» The intercepts of the shaded plane with the axes are ` oo, ` 2b and 2 c respecitvely , weiss indices are ` oo` 2,2,. Reciprocals of We3iss indices ar ` 1/oo, 1/2 , 1/2 or 0, 1/2 ,1/2` or expressed. |
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| 439. |
which of the following is not true about the ionic solids ?A. Bigger ions form the close packed structureB. Smaller ions occcupy either the tetrahedral or the octahedral voids depending upon their size.C. Occupation of all the voids is not necessaryD. The fraction of octahedral or tetrahedral voids occupied depends upon the radii of the ions occupying the voids. |
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Answer» Correct Answer - D d is not ture. Tetrahedral voids are always double the octahedral voids. |
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| 440. |
The packing efficiency of the two dimensional square unit cell show in the adjoining fig ,. Is ` (##PR_CHE_V01_XII_C01_E20_009_Q01.png" width="80%">A. 0.3927B. 0.6802C. 0.7405D. 0.7854 |
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Answer» Correct Answer - D In the two - dimensional packing , packing fraction Area occupied by circles ` (" within the square")/("Area of the square") ` ` ( 2 xx pir^(2))/a^(2) ` AC = `sqrt(AB^(2) + BC^(2)) = sqrt(a^(2) + a^(2)) = sqr2 a ` but AC = 4 r( r= radius of each sphere) ` sqrt2 a= 4r or a = 4/sqrt2 r = 2 sqrt2r` packing fraction ` ( 2xx pi r^(2))/((2 sqrt2 r)^(2))= pi/4 = ( 3.143)/4 = 0.785 i.e, 78.5%` |
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| 441. |
the correct order of the packing effeciency in different types of unit cells is ……….. .A. fcc lt bcc lt simple cubicB. fcc gt bcc gt simple cubicC. fcc lt bcc gt simple cubicD. bcc lt fcc gt simple cubic |
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Answer» Correct Answer - B Packing efficiency, for scc unit cell = 55.4% for bcc unit cell = 68% for fcc unit cell = 74% Thus, the order of packing efficiecy is fcc gt bccgt scc |
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| 442. |
Which of the following defects is also known as dislocation defect ?A. frenkel defectB. Schottky defectC. Non-stoichiometric defectD. simple intersitiial defect |
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Answer» Correct Answer - D In frenkel defect, ions are displcated from lattice sites to occupy interstitial sites. |
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| 443. |
the correct order of the packing effeciency in different types of unit cells is ……….. .A. fcc lt bcc lt simple cubicB. fcc gt bcc gt simple cubicC. fcc lt bcc gt simple cubicD. bcc lt fcc gt simple cubic. |
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Answer» Correct Answer - B fcc `(74%)`, bcc `(68%)`, simple cubic `(52.4%)`. |
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| 444. |
which of the following is not true about the ionic solids ?A. Bigger ions form the close packed structureB. smaller ions either occupy the tetrahedral or the octahedral voids depending upon their sizeC. Occupation of all voids is not necessaryD. the fraction of octahedral or tetrahedral voids occupied depends upon the radii of the ions occupying the voids |
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Answer» Correct Answer - D the fraction of octahedral or tetrahedral voids occupied depends upon the radii of the ions present at the lattice points As , We known the radii of octahedral or tetradral void is related to radii of atoms ( r) as Radius of octahedral void `(R_(0))=0.414r` Radius of tetrahedral void `(R_(0))=0.225 r` where , - r = radius of bigger atom involved. |
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| 445. |
the correct order of the packing effeciency in different types of unit cells is ……….. .A. `fccltbcclt` simpel cubicB. `fccgtbccgtc` simple cubicC. `fccltbcclt` simple cubicD. `bccltfcclt` simple cubic |
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Answer» Correct Answer - B Packing efficiency in different types of unit cells be tabulated as Hence, correct order is fcc (74%)`gt` bcc `gt`(68%) `gt` simple cubic (52%) |
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| 446. |
which of the follwing defects is also known as dislocation defect ?A. Frenkel defectB. Schottky defectC. Non-stoichiometric defectD. Simple interstitial defect. |
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Answer» Correct Answer - A Frenkel defect is also called dislocation defect. In this, the ions are dislocated from lattice sites to occupy interstitial sites. |
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| 447. |
the edge length of the unit cells in terms of the radius of sphere constituting fcc ,bcc and simple cubic unit cells are respectively ………. .A. `2sqrt(2r),(4r)/(sqrt3),2r`B. `(4r)/(sqrt3),2sqrt(2r),2r`C. `2r,2sqrt(2r),(4r)/(sqrt3)`D. `2r,(4r)/(sqrt3),2sqrt(2r)` |
| Answer» Correct Answer - A | |
| 448. |
The fraction of the total volume occupied by the atoms present in a simple cube isA. `pi/4`B. `pi/6`C. `pi/(3sqrt2)`D. `pi/(4sqrt2)` |
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Answer» Correct Answer - D In a simple cube, no. of atoms/unit cell ` = 8 xx 1/8 =1 ` Volume of the atom = ` 4/3 pi r^(3)` volume of the cube = ` a^(3) = ( 2r)^(3) = 8 r^(3)` Fraction occupied = `( 4/3 pi r^(3))/( 8 r^(3) ) = pi/6` |
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| 449. |
A ferromagnetic substance becomes a permanent magnet when it is placed in a magnetic field because:A. all the domains get oriented in the direction of magnetic fieldB. all the domains get oriented in the direction opposite to the direaction o magnetic fieldC. Domains get ori ented randomyD. Domains are not affected by magnetic field |
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Answer» Correct Answer - A when a ferromagnetic substance is placed in a magnetic field it becacomes a permanent mangnet magnet because all the dominas get oriented in the directions of magnetic field even after removal of applied magnetic field. |
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| 450. |
Which of the following statements is (are) correct ?A. The coordination number of each type of ions in CsCl crystal is 8B. A metal that crystallizes in bcc structure has a coordination number of 12C. A unit cell of an ionic crystal shares some of its ions with other unit cellsD. The length of the unit cell in NaCl is 552pm `(r_(Na^(+))=95 "pm" , r_(Cl^(-))=181 "pm")` |
| Answer» Correct Answer - A::C::D | |