InterviewSolution
Saved Bookmarks
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.
| 451. |
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 orrientedd in the direction opposite to the direction of magnetic field.C. domains get oriented randomlyD. domains are not affected by magnetic field. |
|
Answer» Correct Answer - A Ferromagnetic solids can be permanently magnetised and then all the domains get oriented the direction of applied magnetic field. |
|
| 452. |
in the cubic packing , the unit cell has ………. .A. 4 tetrahedral voids each of which is shared by four adjacent unit cellsB. 4 tetrahedral voids within the unit cellC. 8 tetrahedral voids each of the which is shared by four adjacent unit cellsD. 8 tetrahedral voids within the unit cells. |
| Answer» Correct Answer - D | |
| 453. |
What is true about a bcc unit cell?A. Number of atoms in the unit cell is 2B. In addition to atoms at the centre of the body, in the unit cell there are eight different cornersC. `1//8` atom at each corner of the unit cellD. None of the above |
| Answer» Correct Answer - A::B::C | |
| 454. |
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 direction of magnetic fieldC. domains get oriented randomlyD. domains are not affected by magnetic field. |
| Answer» Correct Answer - A | |
| 455. |
Select the correct statements (s)A. Under high pressure, the co-ordination no. increases from `6:6 "to" 8:8`B. Under high pressure, the co-ordination no.decreases from `8:8 " to " 6:6`C. At high temperature, co-ordinate no. decreasesD. At 760 K, CsCl structure changes into NaCl structure |
| Answer» Correct Answer - A::C::D | |
| 456. |
Which of the following is a ferromagnetic compound.A. NiB. CoC. `CrO_(2)`D. All |
| Answer» Correct Answer - 4 | |
| 457. |
Explain why, a salt which does not conduct electricity in the solid state becomes a good conductor in molten state.A. DiamondB. GraphiteC. IodineD. Sodium chloride |
| Answer» Correct Answer - 2 | |
| 458. |
Diamond is:A. a covalent solidB. non-conductorC. a lubricantD. `sp^(3)` hybridised |
| Answer» Correct Answer - A::B::C | |
| 459. |
Which of the following is true for diamondA. Diamond is a good conductor of electricity.B. Diamond is softC. Diamond is a bad conductor of heaet.D. Diamond is made up of C,H and O |
| Answer» Correct Answer - C | |
| 460. |
Which of the following is a good conductor of electricity?A. Diamond is a good conductor of electricity.B. GraphiteC. SiliconD. Amorphous carbon. |
| Answer» Correct Answer - B | |
| 461. |
The lusture of a metal is due toA. Its high densityB. Its high polishingC. Its chemical inertnessD. presence of free electrons |
| Answer» Correct Answer - D | |
| 462. |
Potassium crystallizes in body centered cubic lattice with a unit cell length `a = 5.2 Å` (A) what is the distance betweenn nearest neighbourss? (B) What is the distance between next nearest neighbour ? (C) How many nearest neighbours does each K atom have ? (D) How many next nearest neighbours does each K has ? (E) What is calculated density of crystalline K |
|
Answer» Correct Answer - A::B::C::D (A) `2r = (sqrt3a)/(2) = (sqrt3 xx 5.2)/(2) = 4.5 B9Å` (C) 8 (D) 6 (E) `d = (2 xx 39)/((5.2 xx 10^(-8))^(3) xx 6.02 xx 10^(23)) =` 0.92 g/mL |
|
| 463. |
A compound consisting of the monvalent ions, ` A^(+) , B^(-)` crystallizes in the body -centred cubic lattice. (i) What is the formula of the compound ? (ii) If one of ` A^(+)` ions from the corner is replaced by a monovalent ion `C^(+)`. What would be the simplest formula of the resulting compound ? |
|
Answer» (i) Contribution of ` A^(+)` ions present at the corners to wards unit cell =` 8 xx 1/8 =1` Contribution of `B^(-)` ion present at the body - centre =1 Ration of ` A^(+) : B^(-)` = 1:1 . Hence , the formula is AB. (ii) ` A^(+)` ions at the corners = 7. Hence, their contribution towards unit cell = ` 7/8` ` C^(+)` ion at one corner contributes = `1/8` ` B^(-)` ion at the body centre has contribution =1 . Hence, ratio of A:B :C =` 7/8 : 1/8 :1 = 7: 1 : 8` Formula will be ` A_(7)BC_(8)` |
|
| 464. |
To get n-type semicoductor from silicon, it should be doped with a substance with group no.……A. 2B. 1C. 3D. 5 |
|
Answer» Correct Answer - B |
|
| 465. |
Which of the following point defects are shown by AgBr (s) crystals ? (a) Schottky defect (b) Frenkel defect ( c) metal ecxess defect (d) Metal deficiency defectA. Schottky defectB. Frenkel defectC. Metal excess defectD. metal deficiency defect |
|
Answer» Correct Answer - A AgBr shows both Schottky as well as Frenkel defect. In AgBr, both `Ag^(+)` and `Br^(-)` ions are absent from the lattice causing Schottky defect. However `Ag^(+)` ions are mobile so they have a tendency to move aside the lattice and trapped in interstitial site hence, cause F frendkel defect. |
|
| 466. |
A metal crystallizes into two cubic phases, face-centred cubic and body-centred cubic, which have unit cell lengths `3.5` and `3.0 A`, respectively. Calculate the ration of densities of fcc and bcc.A. 3.12B. 2.04C. 1.26D. 0.72 |
|
Answer» Correct Answer - C `d = (ZM)/(a^(3)N_(A)) (d_(1))/(d_(2)) = (4)/((3.5)^(3)) xx ((3)^(3))/(2) = 1.26` |
|
| 467. |
At very low temperature, oxygen `(O_(2))` freezes and forms a crystalline solid. Which term best describes the solid ?A. Covalent netword crystalsB. Molecular crystalsC. Metallic crystalsD. Ionic crystals |
| Answer» Correct Answer - B | |
| 468. |
Which of the followings point defects are shown by AgBr(s) crystals ? (A) schottky defect (B) Metal excess defect© Metal deficiency defect (d) Metal deficiency defectA. (A) and (B)B. © and (D)C. (A) and ©D. (B) and (D) |
|
Answer» Correct Answer - B |
|
| 469. |
Which defect causes decreases in the density of crystal?A. FrenkelB. SchottkyC. InterstitialD. Intrinsic |
| Answer» Correct Answer - 2 | |
| 470. |
The crystal with metal deficiency defect is:A. NaClB. FeOC. KClD. ZnO |
| Answer» Correct Answer - B | |
| 471. |
The crystal with metal deficiency defect isA. NaClB. FeOC. KClD. ZnO |
|
Answer» Correct Answer - c In FeO, as some Fe may be present as ` Fe^(3+)` and for charge neutality ` 3 Fe^(2+) = 2 Fe^(3+)` . Hence, FeO should have metal deficiency defect. |
|
| 472. |
A sample of ferrous oxide has actual formula ` Fe_(0.93) O_(1.00)` . In this sample what fraction of metal ions are `Fe^(2+)` ions ? What type of non-stoichoimetric defect is present in the sample ? |
| Answer» Metal deficency defect is present in the sample because iron is present in lesser amount than required according to stoichiometric composition . | |
| 473. |
With the help of a labelled diagram shown that there are four octahdedral voids per unit cell in a cubic close packed structure. |
| Answer» Correct Answer - 7 | |
| 474. |
Assertion : Ssemiconductors are solids with conductivities in the intermediate range from ` 10^(-6) - 10^(4) ohm^(-1) m^(-1)` Reason : Intermediate conductivity in semiconductor is due to partially filled valence band.A. Assertion and reason both are corrct statements and reason is correct explanation for assertion.B. Assertion and reson both are correct statements but reason is not correct explanation for asseration .C. Assertion is correct statement but reason is wrong statement .D. Assertion is wrong statement but reason is correct statement . |
| Answer» Correct Reason . Intermediate conductivity of semiconductors is due to small energy gap between filled valence band and empty conduction band. | |
| 475. |
Assertion :-(A) semiconductors are solids with conductivites in the intermediate range from`10^(-6)-10^(4) ohm ^(-1)m^(-1)` Reason :-(R ) internmediate conductivity in semiconductor Is due to partially filled valence band .A. If both assertion and reason and true and reason is the correct explanation of assertion.B. If both assertion and reason and true and reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
|
Answer» Correct Answer - C Conductance of semiconductors lies between metals and insulators, i.e., in therange of `10^(-6)` to `10^(4)ohm^(-1)m^(-1)` |
|
| 476. |
Assertion :-(A) semiconductors are solids with conductivites in the intermediate range from`10^(-6)-10^(4) ohm ^(-1)m^(-1)` Reason :-(R ) internmediate conductivity in semiconductor Is due to partially filled valence band .A. Assertion and reason both are correct statements and Reason is correct explantion for Assertion .B. Asserton and Reason both are correct statement but Reason is not correct explanation for assertion .C. Assertion is correct statement but reason is worng statement .D. Assertion is Wrong statement but Reason is correct statement . |
|
Answer» Correct Answer - C Assertion is correct statement but reason is incorrect statement . semiconductors are solids with conductivites in the intermediate range varie from `10^(-6)-10^(4) Omega ^(-1) m^(-1)` intermediate conuctivity is due to small energy gap between valence band and conduction bond , |
|
| 477. |
Assertion :-(A) semiconductors are solids with conductivites in the intermediate range from`10^(-6)-10^(4) ohm ^(-1)m^(-1)` Reason :-(R ) internmediate conductivity in semiconductor Is due to partially filled valence band .A. Assertion and reason both are corrent statements and reason is correct explanation for assertion.B. Assertion and reason both are corrent statements but reason is not correct explanation for assertion.C. Assertion is corrent statement but reason reason is wrong statement.D. Assertion is wrong statement but reason is correct statement. |
|
Answer» Correct Answer - C Corrcet Reason. Intermediate conductivity of semi-conductors is due to small energy gap between valence band (filled) and conduction band (empty band). |
|
| 478. |
Assertion :- (A) total number of octahedral voids present in unit cell of cubic close of each packing including the one that is present at the body centre . Is four . Reason :- ( R) Besides the body centre there is one octahedral void present at the centre of each of the six faces of the unit cell and each of which is shared between two adjeccent units cells.A. Assertion and reason both are corrent statements and reason is correct explanation for assertion.B. Assertion and reason both are corrent statements but reason is not correct explanation for assertion.C. Assertion is corrent statement but reason reason is wrong statement.D. Assertion is wrong statement but reason is correct statement. |
|
Answer» Correct Answer - C Corrcet Reason. Besides the body centre, there is one octahedral void at the centre of each of the 12 edges. |
|
| 479. |
Assertion : The packing efficiency is maximum for the fcc structure. Reason : The cordination number is 12 in fcc structure.A. Assertion and reason both are corrent statements and reason is correct explanation for assertion.B. Assertion and reason both are corrent statements but reason is not correct explanation for assertion.C. Assertion is corrent statement but reason reason is wrong statement.D. Assertion is wrong statement but reason is correct statement. |
|
Answer» Correct Answer - B Corrcet Explanation. The constituents are closely packed in fcc arrangement. |
|
| 480. |
Assertion : The packing efficiency is maximum for the fcc structure. Reason : The cordination number is 12 in fcc structure.A. If both assertion and reason and true and reason is the correct explanation of assertion.B. If both assertion and reason and true and reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
|
Answer» Correct Answer - B In fcc unit cell, there is ccp arrangment with packing efficiency of 74.01% which is maximum. In ccp arrangment, coordination number is 12. |
|
| 481. |
what is the radius of sodium atom if it crystaliizes in bcc structure with the cell edge of 400 pm? |
|
Answer» Correct Answer - 19.4 ` g//cm^(3) ,` 143.9 pm For BCC, ` r = sqrt3/4 a = 1.732/4 xx 400 = 173.2 ` pm |
|
| 482. |
An element with density 11.2 ` g cm^(-3)` forms a f.c.c lattic with edge lengh of ` 4 xx 10^(-8)` cm. calculate the of atoms mass of the element ( Given : ` N_(A) = 6.022 xx 10^(23) mol^(-1)` |
|
Answer» Correct Answer - `24.12 xx 10^(23) ` atoms `p (Z xx M)/( a^(3)xx N_(A)) ` For element with f.c.c. lattice, Z = 4 ` M = ( p xx a^(3) xx N_(A))/ Z = (( 11.2 " g cm"^(-3)) ( 4xx 10^(-8) "cm")^(3) xx ( 6.022 xx 10^(23) "mol"^(-1)))/4 = 107.9 " g mol"^(-1)` |
|
| 483. |
Why does zine oxide exhibit enhanced electrical conductivity on heating ? |
|
Answer» On heating , zinc oxide loses oxygen as : ` ZnO overset(delta)to Zn^(2+) + 1/2 O^(2) + 2e^(-) ` The ` Zn^(2+)` ions thus formed are eptrapped into the interstitional sites while the electrons are also etnrapped in the neighbouring intersitial sites. These entapped electrons enhance the electrical conductivity of ZnO. |
|
| 484. |
The packing effciency ofa simple cubic crystal is given byA. `sqrt(2)pi//6`B. `sqrt(3)pi//8`C. `pi//6`D. `pi//8` |
|
Answer» Correct Answer - 3 In simple cubic unit cell ,the edge length (or side) of the cube `a` and the radius of atom, `r` are related as `a=2r` The volume of the cubic unit cell=`a^(3)` `=(2r)^(3)=(8r)^(3)` Since a simple cubic unit cell contains only `1`atom , the volume of the volume of the occupied space `=(4)(3)pir^(3)` :.Packing efficiency `=("volume of one atoms ")/("volume of cubic unit cell")xx100%` `=(4//3pir^3)/(8r^(3))xx100` `= (pi)/(6)xx100%` |
|
| 485. |
In fcc unit cell the radius of each atom (sphere) is releated to the edge length ( or side) of the cube asA. `r=(sqrt(3))/(2)a`B. `r=(sqrt(3))/(4)a`C. `r=sqrt(3)a`D. `r=(4)/(sqrt(3))` |
|
Answer» Correct Answer - 2 The length of the body diagonal is equal to `sqrt(3)a` .In bcc unit cell , all the three spheres(atoms) along the diagonal touch each other.therefore ` 4r=sqrt(3a)` `r=(sqrt(3))/(4)a`. |
|
| 486. |
Select the correct statement (s) for the rock -salt structure (NaCl) :A. The tetrahedral voids are smaller than the octhedral sitesB. The octahedral voids are occupied by cations and the tetraherdral sites are emptyC. The radius ratio `(r_(c)//r_(a))` is 0.225D. The radius ratio `(r_(c)//r_(a))` is 0.732 |
|
Answer» Correct Answer - A::B |
|
| 487. |
The fcc structure is often calledA. hexagonal closest packed structureB. tetragonal closest packed structureC. cubic closest packed structureD. triclinic closest packed structure |
|
Answer» Correct Answer - 3 Because the unit cell of ccp structure is fcc unit cell. |
|
| 488. |
The lattice of `CaF_(2)` is called fluorite structure. `SrCl_(2)` has fluorite structure. Which of the following statements is true for `SrCl_(2)` ?A. `Sr^(2+)` are at the corner and face centres of the cubic arrangmentB. `Sr^(2+)` are arranged in bcc latticeC. `a^(-)` are arranged in fcc latticeD. `Cl^(-)` occupy octahedral holes in the lattice |
|
Answer» Correct Answer - A `Sr^(2+)` are at the corners and face centre of the cubic arrangement |
|
| 489. |
An hcp and a ccp structure for a given element would be expected to haveA. The same co-ordinational numberB. the same densityC. the same packing fractionD. all of the above |
|
Answer» Correct Answer - A::C |
|
| 490. |
At room temperature a substance exists in the solid state only whenA. thermal motion dominates over intermolecular forceB. thermal motion is balanced by the intermoleuclar forcesC. thermal motion is susperseded by the intermolecular forcesD. constituent particles are ions |
|
Answer» Correct Answer - 3 In everyday language,we call a substance a solid if we cannot see the flows and change in shape that we associate with liquids.This is possible only when intermolecular forces are stronger than thermal motion. |
|
| 491. |
In calcium fluoride `(CaF_(2))`, the coordinate number of each `Ca^(2+)` ion is `"_______"` and that of each `F^(-)` ion is `"______"`.A. `8,4`B. `4,8`C. `4,4`D. `8,8` |
|
Answer» Correct Answer - 2 In `CaF_(2)` (fluorite) structure,the `Ca^(2+)` ions are located at the face centred cubic lattice points and ,therfore ,have cubic closet packed arrangement ,The fluroide ions `(F^(-)`ions) occupy all the eight tetrahedral voids.Thus there are four `Ca^(2+)` ions and eight `F^(-)` ions in the unit cell of calcium fluoride. since `F^(-)` ion is present in the tetrahedral void ,it is surrounded by four `Ca^(2+)` ions.if we imagine that the unit cell is divided into eight subcubes then each `Ca^(2+)` ion sitting at the face centre is shared by eight minicubes ,Since the centre of each subcube is captured by `F^(-)` ions we can say that each `Ca^(2+)` ions is surrounded by `8F^(-)` ions. |
|
| 492. |
The bond length and bond angles in molecules in the solid state are calculated by:A. X-ray diffraction techniqueB. neutrons bombardmentC. protons bombardmentD. none of these |
|
Answer» Correct Answer - A |
|
| 493. |
Semiconductors posses conducitivity in the range ……. To……. |
|
Answer» Correct Answer - valence band, conduction band |
|
| 494. |
A low molar heat of fusion is expected for a solid that is:A. a covalent solidB. an ionic solidC. a metallic solidD. a molecular solid |
|
Answer» Correct Answer - D Molecular solids have low heat of fusion. |
|
| 495. |
The co-ordination number of calcium fluoride `(CaF_(2))` type structure isA. `1 : 2`B. `4 : 4`C. `4 : 8`D. `8 : 4` |
|
Answer» Correct Answer - C C.N.of `Cu^(2+)` ion = 8, C.N. of `F^(-)`ion = 4 `:.` C.N. of `CaF_(2)` type structure is `8 : 4` |
|
| 496. |
Constituent particles of a solid haveA. vibrational motion onlyB. rotational motion onlyC. translational motion onlyD. all the three types of motion |
|
Answer» Correct Answer - 1 In a solid the constituent particle are very closely packed and the forces of attaction among these particles are so strong that the constituent particles in solids have more or less fixed positions.They can only oscillate about their mean positions.Consequently soids are rigid and have a definite shape and volume . |
|
| 497. |
Constituent particles of a solid haveA. Translatory motion onlyB. Rotatory motion onlyC. Vibtratory motion onlyD. All the above types of motion. |
| Answer» Correct Answer - 3 | |
| 498. |
which of the following favours the existenence of a substance in the solid state ?A. High temperatureB. Low temperatureC. high thermal eneryD. Weak cohesive forces |
|
Answer» Correct Answer - B At low temperature existence of a substance in solid state is due to (a) slow molecular motion and (b) Strong cohesive forces These two forces hold the constituent particles together thus causes existence of substance in solid state. |
|
| 499. |
Which type of solid crystals will conduct heat and electricity?A. ionic crystalsB. Covalent crystalC. metallic crystalsD. molecular crystals |
|
Answer» Correct Answer - C |
|
| 500. |
Constituent particles of a solid haveA. translatory motion onlyB. rotatory motion onlyC. vibratory motion onlyD. all the above types of motion. |
|
Answer» Correct Answer - C Particles of a solid have vibratory motion only. |
|