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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.
| 651. |
A matchbox exhibits `:`A. cubic geometryB. monoclinic geometryC. orthohombic geometryD. tetragonal geometry |
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Answer» Correct Answer - C Orthorhombic geometry has `acancel(=)bcancel(=)c` and `alpha=beta=gamma=90^(@)` . The shape of matchbox obey this geometry. |
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| 652. |
Schottky defect is observed in crystals when ……………. .A. some carions move from their lattice site to interstitial sitesB. equla number of cations and anions are missing from the latticeC. some lattice sites are occupied by electronsD. some imurity is present in the lattice |
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Answer» Correct Answer - B Schottky defect is observed when equal number of cations and anions are missing from their lattice sites . |
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| 653. |
Schottky defect is found inA. NaClB. `BaSO_(4)`C. `MgCl_(2)`D. `CaCl_(2)` |
| Answer» Correct Answer - 1 | |
| 654. |
Which arrangement of electrons leads to ferromagnetism ?A. `uarruarruarruarruarr`B. `darruarrdarruarr`C. `uarruarruarrdarrdarr`D. none of these |
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Answer» Correct Answer - a Ferromagnetism is due to spontaneous alighment of the magnetic dipole in same direction. |
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| 655. |
Ferromagnetism is inA. `uparrow uparrow uparrow uparrow uparrow `B. `uparrow downarrow uparrow downarrow`C. `uparrow uparrow uparrow downarrow downarrow`D. `uparrow uparrow downarrow downarrow downarrow uparrow uparrow uparrow` |
| Answer» Correct Answer - 1 | |
| 656. |
Explain Ferromagnetism with suitable example . |
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Answer» Ferromagnetic Substances : Some substances containing more number of unpaired electrons are very strongly attracted by the external magnetic field . In ferromagnetic substances the Magnetic moments in individual atoms are all alligned in the same direction . Such substances are called Ferromagnetic Substances . In ferromagnetic substances the field strength `B gt gt gt H` . E.g : Fe , Co and Ni . |
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| 657. |
As a result of Frenkel defect ,A. there is no effect on the densityB. there in no effect on the conductivityC. there is no effect on the dielectric constantD. there is no effect on all the three abov. |
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Answer» Correct Answer - A AS a result of Frenkel defect,there is no effect on density . |
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| 658. |
Which of the following statements is not true ?A. Paramagetic substances are weakly attracted by magnetic fieldB. Ferromagnetic substances cannot be magnetised permanentlyC. The domains in antiferromagnetic substances are oppositely oriented with respect to each otherD. Pairing of electrons cancels their magnetic moment in the diamagnetic substances |
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Answer» Correct Answer - B Ferromagnetic substances can be magnetised permanently. Other given statements are true. |
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| 659. |
Non stoichlometric solid among the followingA. MgOB. CaOC. `Na_(@)O`D. TiO |
| Answer» Correct Answer - 4 | |
| 660. |
If Indium is added in small quantity of Ge metal, we getA. An n-type semiconductorB. A p-type semiconductorC. RectifierD. Insulator |
| Answer» Correct Answer - 2 | |
| 661. |
Ferromagnetism is maximum inA. FeB. NiC. CoD. None |
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Answer» Correct Answer - A Ferromagnetism is maximum is Fe out of F,Co and Ni . |
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| 662. |
Which of the following ferromagnetic ?A. NiB. CoC. `Fe_(3)O_(4)`D. All are correct |
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Answer» Correct Answer - D Ni, Co and `Fe_(3)O_(4)` all are ferromagnetic. |
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| 663. |
At zero Kelvin a piece of germaniumA. Frenkel defectB. Schottky defectC. Metal excess defectD. No defect |
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Answer» Correct Answer - B At 0 K, most of the ionic crystals possess no defect. |
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| 664. |
Germanium is an example ofA. An intrinsic semiconductorB. An n-type semiconductorC. A p-type semiconductorD. insulator |
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Answer» Correct Answer - A Germanium (like silicon ) is an intrinsic semiconductor. |
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| 665. |
Select the correct statementA. A cubic close packed structure has eight tetrahedral and six octaedral intersticesB. Graphite has three dimensional crystal latticeC. Diamond has two dimensional crystal latticeD. Coordination number of body centred cubic lattice is eight . |
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Answer» Correct Answer - D Coord. No. of body-centred cubic lattice is eight . |
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| 666. |
First three nearest neighboure distance for primitive cubic lattice are respectively (edge length of unit cell = a):A. `a,sqrt(2a),sqrt(3a)`B. `sqrt(3a),sqrt(2a),a`C. `asqrt(2a),2a`D. `asqrt(3a),2a` |
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Answer» Correct Answer - A |
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| 667. |
Which has hcp crystal structure ?A. NaClB. CsClC. ZnD. RbCl |
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Answer» Correct Answer - C Zn has hcp structure |
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| 668. |
How many atoms can be assigned to its unit cell if an element forms (i) a body centred cubic unit cell (ii) face centred cubic unit cell ? |
| Answer» Correct Answer - (i) 2 (ii) 4 | |
| 669. |
In crystal structure of NaCl, total number of ` Cl^(-)` ions in a unit cell isA. 6B. 4C. 8D. 2 |
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Answer» Correct Answer - B |
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| 670. |
The cubic unit cell of a metal (molar mass= 63.55 `"mol"^(-1)`) has an edge length of 362pm. Its density is `8.92gcm^(-3)`. The type of unit cell isA. PrimitiveB. face centred cubicC. body centredD. End centred |
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Answer» Correct Answer - 2 `rho=(zm)/(N_(0)a^(3))` |
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| 671. |
What is the maximum number of atoms in a hcp crystal structure of an element ? |
| Answer» Correct Answer - 12 | |
| 672. |
How may atoms can be assigned to its unit cell if an element forms (i) body-centred cubic cell (ii) a face -cenrtred cubic cell. |
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Answer» Atoms per unit cell in a body-centred cubic cell = `8 xx 1/8` ( from corners) + 1 ( from body centre )= 2 Atoms per unit in a face- centred cubic cell =` 8xx 1/8 ` ( from corners) + ` 6 xx 1/2` ( from centres ) = 4 |
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| 673. |
In NaCl crystal the `Cl^(-)` ions are in f.c.c. arrangement. Calculate the number of `Cl^(-)` ions in unit cell. |
| Answer» Correct Answer - 4 | |
| 674. |
In `CaF_(2)` " Crystal , ` Ca^(2+)` ions are present in FCC arrangement. Calculate the number of `F^(-)` ions in the unit cell. |
| Answer» No. of ` Ca^(2+)` ions per unit cell = `8xx 1/8 + 6 xx 1/2 = 4` Hence, no of `F^(-)` ions per unit cell =` 2xx4 =8` | |
| 675. |
Which of the following statements is not correct ?A. The fraction of the total volume unoccupied by the atoms in a primitive cell is 0.48.B. Molecular solids are generally volatileC. The number of carbon atoms in a unit cell of Diamond is 4.D. The number of Bravais lattices in which a crystal can be categorized is 14. |
| Answer» the number of C-atoms in a unit cell of diamond is 8 and not 4. | |
| 676. |
Sodium metal crystallises in body centred cubic lattic with cell edge `4.29 Å` .What is the radius of sodium atom ?A. `18.6.^(@)A`B. `1.86.^(@)A`C. 186nmD. 1860pm |
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Answer» Correct Answer - 2 In bcc radius of atom `(r)=(sqrt(3)a)/(4)` |
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| 677. |
(A): With increase in temperature the conductivity of metals decreases. (R): With increase in temperature lattice vibrations increase in metals. `2.4xx10^(24)` atoms.A. Both A and R are true and R is the correct explanation of AB. Both A and R are true and R is not the correct expalantion of AC. A is correct R is wrongD. A is wrong R is correct |
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Answer» Correct Answer - 1 mass one unit cell `=2.39xx1.66xx10^(-24)g` |
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| 678. |
In NaCl crystal, `Ci^(-1)` ions are I FCc arrangement, Calculate the number of ` Cl^(-)` ions in its unit cell. |
| Answer» `Cl^(-)` ion per unit cell = ` 8 xx 1/8 "( from corners)" + 6 xx 1/2` ( form face centres ) = 4. | |
| 679. |
If the positions of ` Na^(+) and Cl^(-)` are interchanged in NaCl, having fcc arrangement of ` Cl^(-)` ions then in the unit cell of NaClA. `Na^(+)` ions will decrease by 1 while ` Cl^(-)` ions will increase by 1.B. `Na^(+)` ions will increase by 1 while `Cl^(-)` ions will decrease by 1C. Number of ` Na^(+) and Cl^(-)` ions will remain the sameD. The crystal structure of NaCl will change. |
| Answer» In NaCl with fcc arrangement of `Cl^(-)` ions arrangemetn of ` Cl^(-)` ion = 14, ` Na^(+)` ions = 13. On interchanging their positions, ` Cl^(-)` ions will be 13 and ` Na^(+)` ions will be 14. | |
| 680. |
Schottky defect.A. NaClB. KClC. CsCl crystallizes in body central cubic type of lattice.D. All of these |
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Answer» Correct Answer - D Schottky defects occurs in highly ionic compounds which have high co-ordination number ex, NaCl,KCl,CsCl. |
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| 681. |
Which one of the following forms a molecular solid when solidified?A. Silicon carbideB. Calcium fluorideC. Rock saltD. Methane |
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Answer» Correct Answer - D Methane forms a molecular solid when solidifier |
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| 682. |
What is the state of hybridisation of carbon atoms in graphite ? |
| Answer» Correct Answer - `sp^(2)` hybridised | |
| 683. |
Which of the following covelent network solids is referred to as pencil lead?A. CorundumB. CarborundumC. QuartzD. Graphite |
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Answer» Correct Answer - 4 Graphite consists of two dimensional sheets of six-membered rings ,the atoms in each sheet are offset slightly from the atoms in the neighboning sheets. The layers (sheets) are held together by the weak van der Waals forces.The strong covalent bonds in graphite account for its hardness.However graphite is slippery to the touch and is effective as a lubricant because the layers can slide over one another. Graphite is used in pencils and ribbons made for computer printers and type writers. |
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| 684. |
Carbon is `"______"` in graphiteA. divalentB. trivalentC. tetravalentD. pentavalent |
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Answer» Correct Answer - 3 In graphite,`C` atoms are arranged in six-membered rings.The `C` atoms are all `sp_(2)` hybridized . each atom is covalently bonded to three other atoms.The remaining unhybridized `2p` orbital is used in `pi` bonding in fact in each layer of graphite there is the kind of delocalized molecular orbital that is peresent in bezene. Note that there is no free valency of `C` in grphite .If has only delocalized `pi` electrons like benzene (we may think grpahite to be polybezene).Because electrons are free to move around in the extenesively delocalized molecular orbital, graphite is a good condutor of electricity in directions along the planes of `C` atoms. |
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| 685. |
Which of the following is a molecular crystalline solids?A. GraphiteB. DiamondC. FullereneD. None of these |
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Answer» Correct Answer - 3 Graphite and diamond are covalent network solids.Graphite,the most common allotrope of carbon and the most stable under normal conditions, is a cystalline covalent network solids that consists of two -dimensional sheets of fused six-membered rings . Each `C` atom is `sp^(3)` . hybrized and is bonded with tetrahedral geometry to three other carbons. The diamond form of elementals carbon is a covalent network solids in which each carbon atom is `sp^(3)` hybrized and is bonded with tetrahedral geometry to four other carbons. In addition to graphite and diamond a third, crystalline allotrope of carbon called Buckminster fullerene was discovered in `1985` as a constituent of soot.Fullerence is a molcular sold consisting of spherical `C_(60)` molcules with the extraordinary shpae of soccor ball ,the `C_(60)` ball has `12` pentagonal and `20` hexagonal faces ,with each `C` atom `sp^(2)` hybrodized and bonded graphite and fullerence are a group of carbon allotropes called nanotubes Carbon nanotubes are tubular structures made of repeating six-membered rings ,as if a sheet of graphite were rolled up .Typically the tubes have a diameter of about `2-30`nm and a length of up to `1mm`. Graphite is the black, slippery substance used as the "lead" in pencils as an electrode material in batteies and as a lubricant in locks.All these propeties result from its sheet like structure ,Air and water molecules can adsorb onto the flat faces of the sheets,allowing the sheets to slide over one another and givning grphite its greasy felling and lubricating properties . Graphite is mores stable than diamond at normal pressures.(on account of the possibility of resonance ) but can be converted into diamond at very high pressure .Some industrial diamonds are now made from graphite by applying `150,000` atm presuure at high temperatures. Fullerence ,black and shiny like graphite is the subject of active current research becuase of fits interesting electronic propertied,When allowed to react with `Rb` metal a superconduting material called rubidium fulleride `Rb_(3)60` is formed .Carbon nanotubes are being studued for use as fibre in the structural composites used to make gold clubs ,bicycle frames,boats and airplanes.On a mass basis,nanutubes are upt to tne times as strong as steel. |
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| 686. |
A solid AB has the NaCL structure, If radius of cation `A^(+)` is 120 pm, calculate the maximum possible value of the radius of the anion `B^(-)` |
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Answer» We know for the NaCl structure, for maximum of radius of `B^(-)`, the ratio `r^(+)//r^(-)` should be minimum for octahedral voild i.e., 0.414. Radius of cation/radius of anion = 0.414 `(r_(A))/(r_(B)) = 0.414 rArr r_(B) = (r_(A))/(0.414) = (120)/(0.414) = 290` pm. |
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| 687. |
If a non-metal is added to the interstitial sites of a metal, then the metal becomesA. More ductileB. Less tensileC. Less mailleableD. Softer |
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Answer» Correct Answer - a On adding non-metal , the metal becomes less tensle |
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| 688. |
which of the following is not a characteristic of a crystalline solid ?A. Definite and characteristic heat of fusionB. Isotropic natureC. A regular periodically repeated pattern of arrangement of constituent particles in the entire crystalD. A true solid. |
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Answer» Correct Answer - B crystalline solids are not isotropic because their thermal and optical properties change with change in direction. These are anisotropic in nature. |
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| 689. |
Which of the following is an amorphous solid ?A. Graphite (C)B. Quartz glass `(SiO_(2))`C. Chrome alumD. Silicon carbide (siC) |
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Answer» Correct Answer - B Quartz glass `(SiO_(2))` is an amorphous solid. |
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| 690. |
`NaCI` shown Schottky defect and `AgCI` frenkel defect .Their elelctrical conductivity is due toA. motion of ions and not the motion of electronsB. motion of electrons and not the motion of electronsC. lower coordination number of `NaCI`D. higher coordination number of `AgCI` |
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Answer» Correct Answer - a lons are displaced from one place to another |
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| 691. |
Write the difference between Frenkel and Schottky defects.A. Nucleus defectsB. Non-crystal defectsC. Crystal defectsD. None of these |
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Answer» Correct Answer - C Both are stoichiometric cyrstalline defects. |
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| 692. |
Certain crystals produce electric signals on application of pressure .This phenomenon is calledA. PyroelectricityB. FerroelectricityC. PeizoelectricityD. Ferrielectricity. |
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Answer» Correct Answer - C When polar crystal is subjected to a mechanical stress, electricity is produced - a case of piezoelectricity. Reversely. If electric field is applied, mechanical stress is developed Piezoelectric crystal acts asa mechanical electrical transductor. |
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| 693. |
Assertion: Quasi-crystals form when certain molten alloys cool very slowly. Reason: quasi-crystals have shorts-range as well as long-range order in their arrangement.A. If both assertion and reason are true and the reason is the correct explanantion of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertion.C. If assertion is true but reason is false.D. If the assertion and reason both are false. |
| Answer» Correct Answer - B | |
| 694. |
The oxide which shows metallic conduction isA. `ReO_(3)`B. `VO`C. `CrO_(2)`D. all of these |
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Answer» Correct Answer - d All are conductors show insulation at certain tempeerature |
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| 695. |
Assertion : On beating ferromagnetic or ferromagnetic substance , they become paramagnetic Reason The electrons change their spin on heating |
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Answer» Correct Answer - a All magnitically ordered solids (ferromagnatic and untiferromegnetic solid) transform in the paratamgnetic size at high temperature due so the randomisation of spin |
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| 696. |
Select the correct matchA. Ferroelectricity B. Anti-Ferroelectricity C. Both of the aboveD. None of the above |
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Answer» Correct Answer - c When polar crystal is subjected in a mechanical stress electricity is producted it is celled plezoelectricity Pezonelectric crystal with permanted dipoles (demains algred in same direction ) are said to have frecelectricity as in (a) and with zero dipole (demkain aligned equally) in opposite direction are said to have anti feroectricity as in (b) |
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| 697. |
Certain crystals produce electric signals on application of pressure .This phenomenon is calledA. PytroelectricityB. FerroectricityC. PiezoelectricityD. Ferrelectricity |
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Answer» Correct Answer - c When polar crystal is subjected in a mechanical stress electricity is producted - a case of plezoecricity reversly if electric fied is applied mechanical stress a devoloped piczoelectric crystal acts as a mechanical electrical transiductor |
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| 698. |
HgO is prepared by two different methods: one shows yellow colour while the other shows red colour. The difference in colour is due to difference inA. electronic d-d transitionsB. particle sizeC. Frenkel defectD. Schottkey defect |
| Answer» Correct Answer - B | |
| 699. |
Which one of the following metal oxide is antiferromagenetic in nature?A. `MnO_(2)`B. `TiO_(2)`C. `VO_(2)`D. `CrO_(2)` |
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Answer» Correct Answer - A `MnO_(2)` is antiferromagnetic. |
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| 700. |
In a cubic crystal structure, divalent metal-ion is located at the body -centered position, the smaller tetravalent metal ions are located at each corner and the `O^(2-)` ions are located half way along each of the edges of the cube. The number of nearest neighbour for oxygen isA. 4B. 6C. 2D. 8 |
| Answer» Correct Answer - C | |