1681 + Interview Questions in SOLID-STATE IN GENERAL AWARENESS Page 7 InterviewSolution

301.	The fraction of total volume occupied by atoms in a simple cube isA. `(pi)/(2)`B. `(sqrt(3)pi)/(8)`C. `sqrt(2pi)/(6)`D. `(pi)/(6)`
Answer» Correct Answer - d In simple cubic arrangement no of atoms `= 1` `a = 2r` `:.` packing fraction `= ("Volume occupied by one atom")/( "Volume of unit cell")` `((4)/(3) pi r^(3))/(a^(3)) = ((4)/(3) pi r^(3))/((2r)^(3)) = (pi)/(6)`

Discussion

302.	The fraction of total volume occupied by atoms in a simple cube isA. `sqrt3pi//8`B. `pi//6`C. `pi//3`D. `sqrt2pi//3`
Answer» Correct Answer - B Packing factor in `sc = pi//6`.

Discussion

303.	The fraction of total volume occupied by atoms in a simple cube isA. `pi//6`B. `sqrt(3pi)//8`C. `sqrt(2pi)//6`D. `pi//3`
Answer» Correct Answer - 1 `(1xx(4)/(2)pir^(3))/(a^(3))=((4)/(3)pir^(3))/((2r)^(3))=(pi)/(6)`

Discussion

304.	The radius of the metal atom can be expressed in terms of the length of a unit cell is `:`A. it is `a//2` for simple cubic latticeB. it is `(sqrt(3)a//4)` for b.c.c. latticeC. it is `(a//2sqrt(2))` for F.C.C. latticeD. All of the above
Answer» Correct Answer - 4

Discussion

305.	A solid has a `b.c.c.` structure . If the distance of closest approach between the two atoms is `1.73 Å`. The edge length of the cell is `:`A. `sqrt(2)p m`B. `sqrt((3//2))p m`C. `200 p m`D. `142.2p m`
Answer» Correct Answer - 3 `2r=(sqrt(3)a)/(2)rArra=(2(2r))/(sqrt(3))=(2xx1.73)/(1.73)=2A=200p m`

Discussion

306.	A solid has a bcc structure. If the distance of closest approach between the two atoms is `1.73.^(@)A`. The edge length of the cell isA. 200 pmB. `(sqrt3)/(sqrt2) pm `C. 142.2 gmD. `sqrt2`
Answer» Correct Answer - A `r_("atom") = (sqrt3)/(4)` a , Also closest approach in bcc lattice is `1/2` of body diagonal , i.e. `(sqrt3)/(2) a = 1.73 Å` or `a=(1.73xx2)/(sqrt3) = 1.966Å = 199.6` pm

Discussion

307.	Molecuels ions and their magnetic properties are given below `{:("Molecular/ion","Magnetic property"),(C_(6)H_(6),"Antiferromagnetic"),(CrO_(2),"Ferrimagnetic"),(MnO,"Ferromagnetic"),(Fe_(3)O_(4),"Paramagnetic"),(Fe^(3+),"Diamagnetic"):}` The correctly matched pairs in the above isA. i-5,ii-3iii-2,iv-1,v-4B. i-3,ii-5,iii-1,iv-4,v-2C. i-5,ii-3,iii-1,iv-2,v-4D. i-5,ii-3,iii-1,iv-4,v-2
Answer» Correct Answer - C `C_(6)H_(6)` is diamagnetic (i-5) `CrO_(2)` is ferromagnetic (ii-3) `MnO` is antiferromagnetic (iii-1) `Fr_(3)O_(4)` is ferrimagnetic (iv-2) `Fe^(3+)` is paramagnetic with 5 unpaired electrons (v-4).

Discussion

308.	Select the incorrect statement `:`A. Stiochiometery of crystal remains uneffected dure to Schottky defectB. Frenkel defect is usually shown by ionic compounds having low coordinaiton numberC. F-centres generation is responsible factor for imparting the colour to the crystalD. Density of crystal always increases due to substitutional impurity defect.
Answer» Correct Answer - D

Discussion

309.	What type of interactions hold together the molecules in a polar crystalline solid ?
Answer» Dipolar-dipolar interactions hold together the molecules in a polar crystalline solid.

Discussion

310.	If the pressure on a `NaCI` structure in increases , then its coordination number willA. IncreasesB. DecreasesC. Remain the sameD. Either (b) or (c)
Answer» Correct Answer - A `underset((6.6"cor-ord"))(NaCl) "structure"underset(760K)overset(" High pressure")hArrunderset(("8.8co-ord"))(CsCl)"structure"`

Discussion

311.	The pyknometric density of sodium chloride crystal is `2.165xx10^(3)kg m^(-3)` while its `X` ray density is `2.178xx10^(3)kg m^(-3)` the fraction of unoccupied sites in `NaCl` crystal isA. `5.96xx10^(-3)`B. `5.96`C. `5.96xx10^(-2)`D. `5.96xx10^(-1)`
Answer» Correct Answer - A Difference `=2.178xx10^(3)-2.165xx10^(3)=0.013xx10^(3)`

Discussion

312.	The pyknometric density of sodium chloride crystal is `2.165xx10^(3)kg m^(-3)` while its `X` ray density is `2.178xx10^(3)kg m^(-3)` the fraction of unoccupied sites in `NaCl` crystal isA. 5.97B. `5.97xx10^(-2)`C. `5.97xx10^(-1)`D. `5.97xx10^(-3)`
Answer» Correct Answer - D Fraction of unoccupied sites `=("X-ray density-pyknometric denstiy")/("X-ray density")` `=(2.178xx10^3-2.165xx10^3)/(2.178xx10^3)=5.97xx10^(-3)`

Discussion

313.	In a face centred cubic lattice, a unit cell is shared equally by low many unit cells ?A. 8B. 4C. 2D. 6
Answer» Correct Answer - D In fcc, a unit cell is shared equally by six unit cells.

Discussion

314.	The pyknometric density of sodium chloride crystal is `2.165xx10^(3)kg m^(-3)` while its `X` ray density is `2.178xx10^(3)kg m^(-3)` the fraction of unoccupied sites in `NaCl` crystal isA. `5.96xx10^(-1)`B. `5.96xx10^(-3)`C. `5.96`D. `5.96xx10^(-2)`
Answer» Correct Answer - 2 `X` ray density is higher because corresponds to occupied space only as `X`-rays are diffracted by constituet particles.On the hand ,pyknometric density is lower as it correspondense to occupied as well as unoccupied space. Thus, the fraction of unoccupied site in `NaCl` crystal is given as `"X ray density -pyknometric density(u"/("X-ray density (occupied s")` `=(2.178xx10^(3)-2.165xx10^(3))/(2.178xx10^(3))` `=(0.013xx10^(3))/(2.178xx10^(3))` `=0.00596=5.96xx10^(-3)`

Discussion

315.	In a face centred cubic lattice unit cell is shared equally by how many unit cells?A. `4`B. `2`C. `6`D. `8`
Answer» Correct Answer - 3 A cubic unti cell has six faces. Therefore, in a cubic lattice (irrespective of its nature) cubic unit cell is shared equally by `6` unit cells.

Discussion

316.	A compound formed by elements `A` and `B` crystallises in a cubic structure where `A` atoms are present at the corners of a cube and the `B` atoms are present at the face centres.The formula of the compound isA. `A_(2)B`B. `AB_(3)`C. `AB`D. `A_(3)B`
Answer» Correct Answer - 2 Each atom of a corner is shared between eight adjacent unit cells,Four unit cells in the same layer and four unit cells of the upper (or lower) layer.Therfore only `1//8`th of an atom (or molecule or ion) actually belongs to a particular unit cell). since the cubic unit cell `8` atoms on its corners ,the total number of `A` atoms inone unit cell is `=8xx(1)/(8)=1 "atom"` Each atom located at the face-centre is shared between two adjacent unit cell and hence only `1//2` of each atom belongs to a unit cell. Since each cubic unit cell has `6` atoms on its face-centres the total number of `B` atoms in one unit cell is `=6xx(1)/(2)=3 "atoms"` Thus the empericle formula of the compound is `AB_(3)`.

Discussion

317.	A compound formed by elements `X` and `Y` crystallises in a cubic structure in which the `X` atoms are at the corners of a cube and the `Y` atoms are at the face centres.The formula of the compound isA. `XY_(3)`B. `X_(3)Y`C. `XY`D. `XY_(2)`
Answer» Correct Answer - 1 Exclusively contribution `X` atoms per unit cell `=8xx(1)/(8)=1` Exclusive contribution of `Y` atoms per unit cell `=6xx(1)/(2)=3` Simplest whole number ratio of atoms is `1:3` Hence the empirical formule is `XY_(3)`.

Discussion

318.	A compound formed by elements A and B crystallises in cubic structure in which A atoms are at the corners of the cube while B atoms are at the centre of cubic. Formula of the compound isA. ABB. `AB_(2)`C. `A_(2)B`D. `AB_(4)`
Answer» Correct Answer - A A atoms are at eight cornersof the cube. Therefore, the number of A atoms in the unit cell `=(8)/(8)=1` , Atoms B per unit cell = 1. Hence, the formula is AB.

Discussion

319.	A compound contains two types of atoms X and Y. it crystallises in a cubic lattice with atoms X at the corners of the unit cell and atoms Y at the body centre. The simplest possible formula of this compound isA. `X_(8)Y`B. `X_(2)Y`C. XYD. `XY_(8)`
Answer» Correct Answer - 3 `X=8xx(1)/(8)Y=1xx1`

Discussion

320.	The volume of atom present in a face-centred cubic unit cell of a metal (`r` is atomic radius ) isA. `(20)/(3)pir^(3)`B. `(24)/(3)pir^(3)`C. `(12)/(3)pir^(3)`D. `(16)/(3)pir^(3)`
Answer» Correct Answer - 4 `v=(4)/(3)pir^(3)` In fcc `v=4xx(4)/(3)pir^(3)=(16)/(3)pi r^(3)`

Discussion

321.	Assertion (A) : Non-stoichiometric compounds are called Bertholide compounds. `NaCl` and `KCl` crystal, when heated in an atmosphere of `Na` and `K` varpours, respectively, they impart violet and yellow colours to `NaCl` and `KCl`, respectively. Reason (R ) : Metal excess defect is due to the presence of extra cations atg the interstitial sites. The excess metal ions move to the interstitial sites and the electrons to the neighbouring sites. The colour results byt the excitation of these electrons by absorbing suitable energy from visible light. When the excited electroon comes back to the ground state, there is emission of radiation in the visible region and gives complimentary colour.A. If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`B. If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`C. If `(A)` is correct, but `(R)` is incorrect.D. If both `(A)` is incorrect, but `(R)` is correct.
Answer» Correct Answer - D Correct (A): `NaCl` and `KCl` impart yellow and violet colour, respectively. (R) is correct but not the correct explanation of (A).

Discussion

322.	Assertion (A) : Graphite is an example of tetragonal crystal system. Reason (R ) : For a tetragonal system, `a = b != c` and `alpha = beta = 90^(@), gamma = 120^(@)`.A. if both (A) and ® are correct , and ® is correct explanartion of (AB. if both (A) and ® are correct , but ® is nmot the correct explanation ofC. if (A) is correct , but ® is incorrect.D. if both (A) and ® are icorrect .
Answer» Correct Answer - D Correct(A): Graphite is an example of (a). Crystal system in which each C-atom is `sp^(2)` hybridized and is linked to three other C-atom in a hexagonal planr structure. Correct (R): For tetragonal system, `a=bcancel=c` and `alpha=beta=gamma=90^(@)`. for hexagonal systems. `a=bcancel=c` and `alpha=beta=90^(@),gamma=120^(@)`

Discussion

323.	Assertion (A) : Graphite is an example of tetragonal crystal system. Reason (R ) : For a tetragonal system, `a = b != c` and `alpha = beta = 90^(@), gamma = 120^(@)`.A. If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`B. If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`C. If `(A)` is correct, but `(R)` is incorrect.D. If both `(A)` and `(R)` are incorrect.
Answer» Correct Answer - D Correct (A): Graphite is an example of hexagonal crystal system in which each `C-`atom is `sp^(2)` hybridized and is linked to three other `C-`atom in a hexagonal planar structure. Correct (R): For tetragonal system, `a = b ne c` and `alpha = beta = gamma = 90^(@)`. For hexagonal systems, `a = b ne c` and `alpha = beta = 90^(@), gamma = 120^(@)`.

Discussion

324.	Assertion: Graphite is an example of tetragonal crstal system. Reason: For a tetragonal system. `a=bnec,alpha=beta=90^(@),gamma=120^(@)`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 - D Graphite is hexagonal system and for tetragonal all three angles are `90^(@)`.

Discussion

325.	The molecule having three fold axis of symmetry is :A. `NH_(3)`B. `C_(2)H_(4)`C. `CO_(2)`D. `SO_(2)`
Answer» Correct Answer - a In `NH_(3)` molecule the original appozance is optated as a result of rotation through `120^(@)` such an axis is steel in be an axis of three fold symmetry or a third axis

Discussion

326.	Which of the crystal systems has all the axial angles equal but not equal to `90^(@)`?A. CubicB. TetragonalC. OrthorhombicD. Rhombohedral
Answer» Correct Answer - 4 Rhomohedral: `a=b=c,alpha=beta=gamma!=90^(@)` Cubic :`a=b=c,alpha=beta=gamma=90^(@)` Tetragonal: `a=b!=c,alpha=beta=gamma=90^(@)` Orthorhombic: `a!=b!=c,alpha=beta=gamma=90^(@)`

Discussion

327.	Crystal systems in which no two axial lengths are equal areA. TetragonalB. OrthorhombicC. MonoclinicD. Triclinic
Answer» Only (a) is wrong because in tetragonal system , ` a= b ne c`. In all other cases ` a ne b ne c` .

Discussion

328.	`{:(" Column I ( Crystal system)", "( Column II (Axial ratio)"),("(A) Tetragonal", "(p)" a ne b ne c"," alpha = beta = gamma = 90^(@)),("(B) Rhombic" , "(q)" a = b ne c"," alpha = beta = gamma = 90^(@)),("(C)Monoclinic" , "(r)" a ne b ne c"," alpha ne beta ne gamma ne 90^(@)),("(D) Triclinic" , "(s)" a ne b ne c"," alpha = gamma = 90^(@) ne beta):}`A. A-s , B-r , C-p, D-qB. A-q , B-r , C-q , D-pC. A-r, B-p, C-q, D-sD. A-p , B-q , C-r , D-s
Answer» Correct Answer - b

Discussion

329.	Which of the crystal systems have all the axial distances (or edge lengths )equal?A. Cube and rhombohedralB. Cubic and hexagonalC. Cubic and tetragonalD. Only cubic
Answer» Correct Answer - 1 Cubic `(a=b=c)` and rhombohedral `(a=b=c)`, Hexagonal `(a=b!=c)` tetragonal `(a=b!=c)`.

Discussion

330.	The crystal system without any element of symmetry isA. monoclinicB. hexagonalC. triclinicD. cubic
Answer» Correct Answer - 3

Discussion

331.	A certain crystal has (i) density = `0.456 cm^(-3)` , (ii) a fourfold axis of symmetry and (iii) 4 molecules per unit cell. Side lengths of the unit cell are a = b = 658 pm and c = 593 pm. Calculate the molar mass in g `mol^(-1)`.A. `16.20`B. `17.62`C. `19.25`D. `23`
Answer» Correct Answer - B

Discussion

332.	The presence of F-centres in a crystal makes itA. conductingB. colourlessC. colouredD. None of these
Answer» Correct Answer - C

Discussion

333.	What are F-centres in ionic crystals ? Why are crystals having F-centres are paramagnetic in nature.A. lattice sites containing electronsB. intersitial sites containing electronsC. lattice sites that are vacantD. intertitial sites containing cations
Answer» Correct Answer - 1

Discussion

334.	Which of the following compounds is metallic and paramagnetic ?A. `T_(i)O_(2)`B. `CrO_(2)`C. `VO_(2)`D. `MnO_(2)`
Answer» Correct Answer - B `T_(i)O_(2)` is metallic as well as paramagnetic in nature

Discussion

335.	why are liquids and gases categorised as fuids ?
Answer» Both liquids and gases are categorised as fluids since they have in general, tendency to flow. This is possible because the different layers of particles or molecules can move past or flow over one another.

Discussion

336.	In an fcc unit cell, atoms are numbered as shown below The atoms not rouching each other are (Atom numbered `3` is face center of front face)A. 3 and 4B. 1 and 3C. 1 and 2D. 2 and 4
Answer» In fcc structure , corner atoms do not touch each other (atoms 1 and 2), but every face center atom touches corners, Moreover, every face center atom touches every other face center atom provided it is not the oppostie face center atom in an fcc unit cell. i. Atoms 3 and 4 are touching each other where center-to-center distance `=(a)/sqrt(2)` ii. Atom 1 and 2 are not touching each other. iii. Atoms 2 and 4 are touching each otehr where center-to-center distance `=(a)/sqrt(2)`.

Discussion

337.	Which of the following statement regarding defects in solids is/are correct?A. Schottky defect has no effect on the physical properties of solidsB. Frenkel defect is a dislocation defectC. Frenkel defect is usually favoured by a very small difference in the sizes of cation and anionsD. Trapping of proton in the lattice leads to the formation of F-centres.
Answer» Correct Answer - B Except for the statement (b) all other statements are false

Discussion

338.	which of the following statements are correct ?A. The coordination number of each type of ion in CsCl crystal is 8.B. A metal that crystallizes in bcc structure has coordination number of 12.C. A unit cell of an ionic crystl shares some of its ions with other unit cells.D. The length of the edge of unit cell of NaCl is 552 pm `( r_(Na^(+)) = 95 " pm " , r_(Cl^(-)) = 181 "pm")`
Answer» (d) is correct because length of unit cell =` 2(r_(Na^(+)) + r_(Cl^(-)))= 2 ( 95 + 181)` pm a and b are also correct. Only (b) is wrong because for a metal with bcc structure. Coordination number = 8.

Discussion

339.	The radius of an atom of an element is `500` pm. If it crystallizes as a face-centred cubic lattice, what is the length of the side of the unit cell?
Answer» For `fc c, r = (a)/(2sqrt2)` or `a = 2 sqrt2 r = 2 xx 1.414 xx 500` pm `= 1414` pm

Discussion

340.	The correct statement(s) regarding defects in solids is (are)A. Frenkel dectes are usually favoured by a very small difference in the size of the cation and anionB. Frenkel defect is dislocation defectC. Trapping of an electron in the lattice leads to the formation of F-centreD. Schottky defects have no effect on the physical properties of solids
Answer» Frenkel defect is also called dislocation defect because smaller ions are dislocated from their lattice sites into the interstitial sites. Hence, (b) is correct. Trapping of an electron leads to be formation of F -centre . Hence (c ) is correct.

Discussion

341.	Sodium has a `bc c` structure with nearest neighbour distance of `365.9` pm. Calculate its density. (Atomic mass of sodium `= 23`)
Answer» For the `bc c` strucutre, nearest neighbour distance `(d)` us related to the edge `(a)` as `d = (sqrt3)/(2) a` or `a = (2)/(sqrt3)d = (2)/(1.732) xx 365.9 = 422.5` pm For `bc c` sturcture, `Z_(eff) = 2` For sodium, `Aw = 23` `:. r = (Z_(eff) xx Aw)/(a^(3) xx N_(A) xx 10^(-30))` `= (2 xx 23)/((422.5)^(3) xx (6.02 x10^(23)) xx 10^(-30))g cm^(-3)` `= 1.51 g cm^(-3)`

Discussion

342.	Sodium has a `bc c` structure with nearest neighbour distance of `365.9` pm. Calculate its density. (Atomic mass of sodium `= 23`)A. `1.5g//cm^(3)`B. `3g//cm^(3)`C. `4g//cm^(3)`D. `5g//cm^(3)`
Answer» For the bcc structure, nearest neighbour distance (d) is related to the edge (a) as `d=sqrt(3)/(2)a ` or `a=(2)/sqrt(3)d=(2)/(1.732)xx365.9=422.5`pm For bcc structure, `Z_(eff)=2` For sodium .Aw=23 `therefore r=(Z_(eff)xxA_(w))/(a^(3)xxN_(A)xx10^(-30))=(2xx23)/((422.5)^(3)xx(6.02xx10^(23))xx10^(-23))gcm^(-3)` `=1.51g cm^(-3)`

Discussion

343.	In a solid lattice the cation has left a lattice sirte and is located at an interstital position , the lattice defect isA. Interstitial defectB. velency defectC. Frenkel defectD. Schottky defect
Answer» Correct Answer - c When cation shift lattice to interstitial site , the defect is called frenkel defect

Discussion

344.	Assertion: Increase in dielectric constant is observed for crystals having Frenkel defect Reason: Similarly charged cations come closer in the crystal latticeA. If both assertion and reason are correct and reason is correct explanation for assertionB. If both assertion and reason are correct but reason is not correct explanation for assertionC. If assertion is correct but reason is incorrectD. If both assertion and reason are incorrect
Answer» Correct Answer - A Assertion is the correct explanation for statement for statement -1

Discussion

345.	In a solid lattice the cation has left a lattice sirte and is located at an interstital position , the lattice defect isA. Interstitial defectB. Vacancy defectC. Frenkel defectD. Schottky defect
Answer» Correct Answer - C When cation shifts from lattice to interstitial site, the defect is called frenkel defect.

Discussion

346.	In `AgCl`, the `Ag^(o+)` ions are deisplaced from their lattice position to an interstitial position. Such a defect is calledA. Schottky defectB. Frenkel defectC. Wadsley defectD. Colour centre
Answer» Correct Answer - B Same explanation as in Q. 4 above.

Discussion

347.	In a solid lattice, the cation has left a lattice site and is located on interstitial position. The lattice defect isA. n-typeB. p-typeC. Frenkel defectD. schottky defect
Answer» Correct Answer - B

Discussion

348.	What are f-centers ?
Answer» `to` f-centers are the anionic sites occupied by unpaired electrons . `to` These impart colour to cyrstals . This colour is due to the excitation of electrons when they absorb energy from the visible light . `to` f- centres are formed by heating alkyl halide with excess of alkali metal . E.g : NaCl crystal heated in presence of Na-vapour yellow colour is produced due to f-centres .

Discussion

349.	Which of the following expression is correct in case of a CsCl unit cell (edge length, a)?A. `r_(c)+r_(a)=a`B. `r_(c)+r_(a)=a//sqrt2`C. `r_(c)+r_(a)=sqrt3a//2`D. `r_(c)+r_(a)=a//2`
Answer» Correct Answer - C

Discussion

350.	Give reason: (i) In stochiometric defects, NaCl exhibits schottky defect and not Frenkel defect. (ii) Silicon on doping with phosphorus forms n-type semiconductor . (iii) Ferrimagnetic substances show better magnetisation than antiferromagnetic substences.
Answer» (i) Schottky defect is shown by those compounds which have small difference in the size of catio and anoin whereas Frenkel defect is shown by those compounds which have large difference in the size of cation and anion. As the difference in the size of `Na^(+) and Cl^(-)` ions is small, hence it shows schoottky defect. (ii) Silicon belongs to Group 14 whereas phosphorus blongs to Group 15. s phosphorus has one extra electron than silicon, this extra electron makes silicon a semiconductor. Hence, we get n-type semicondutor. (iii) Ferrimagnetic substances have as unequal number of electrons with spin in the opposite direction. Hence, they have a net magnetic moment. Antiferromagnetic substances have equal number of electrons with spin in the opposite direction. Hence, their net magnetic moment is zero. For this reason, ferrimagnetic subtances show better magnetism tha antiferromagnetic substances.

Discussion

Explore topic-wise InterviewSolutions in .

The fraction of total volume occupied by atoms in a simple cube isA. `(pi)/(2)`B. `(sqrt(3)pi)/(8)`C. `sqrt(2pi)/(6)`D. `(pi)/(6)`

The fraction of total volume occupied by atoms in a simple cube isA. `sqrt3pi//8`B. `pi//6`C. `pi//3`D. `sqrt2pi//3`

The fraction of total volume occupied by atoms in a simple cube isA. `pi//6`B. `sqrt(3pi)//8`C. `sqrt(2pi)//6`D. `pi//3`

The radius of the metal atom can be expressed in terms of the length of a unit cell is `:`A. it is `a//2` for simple cubic latticeB. it is `(sqrt(3)a//4)` for b.c.c. latticeC. it is `(a//2sqrt(2))` for F.C.C. latticeD. All of the above

A solid has a `b.c.c.` structure . If the distance of closest approach between the two atoms is `1.73 Å`. The edge length of the cell is `:`A. `sqrt(2)p m`B. `sqrt((3//2))p m`C. `200 p m`D. `142.2p m`

A solid has a bcc structure. If the distance of closest approach between the two atoms is `1.73.^(@)A`. The edge length of the cell isA. 200 pmB. `(sqrt3)/(sqrt2) pm `C. 142.2 gmD. `sqrt2`

What type of interactions hold together the molecules in a polar crystalline solid ?

If the pressure on a `NaCI` structure in increases , then its coordination number willA. IncreasesB. DecreasesC. Remain the sameD. Either (b) or (c)

The pyknometric density of sodium chloride crystal is `2.165xx10^(3)kg m^(-3)` while its `X` ray density is `2.178xx10^(3)kg m^(-3)` the fraction of unoccupied sites in `NaCl` crystal isA. `5.96xx10^(-3)`B. `5.96`C. `5.96xx10^(-2)`D. `5.96xx10^(-1)`

The pyknometric density of sodium chloride crystal is `2.165xx10^(3)kg m^(-3)` while its `X` ray density is `2.178xx10^(3)kg m^(-3)` the fraction of unoccupied sites in `NaCl` crystal isA. 5.97B. `5.97xx10^(-2)`C. `5.97xx10^(-1)`D. `5.97xx10^(-3)`

In a face centred cubic lattice, a unit cell is shared equally by low many unit cells ?A. 8B. 4C. 2D. 6

The pyknometric density of sodium chloride crystal is `2.165xx10^(3)kg m^(-3)` while its `X` ray density is `2.178xx10^(3)kg m^(-3)` the fraction of unoccupied sites in `NaCl` crystal isA. `5.96xx10^(-1)`B. `5.96xx10^(-3)`C. `5.96`D. `5.96xx10^(-2)`

In a face centred cubic lattice unit cell is shared equally by how many unit cells?A. `4`B. `2`C. `6`D. `8`

A compound formed by elements `A` and `B` crystallises in a cubic structure where `A` atoms are present at the corners of a cube and the `B` atoms are present at the face centres.The formula of the compound isA. `A_(2)B`B. `AB_(3)`C. `AB`D. `A_(3)B`

A compound formed by elements `X` and `Y` crystallises in a cubic structure in which the `X` atoms are at the corners of a cube and the `Y` atoms are at the face centres.The formula of the compound isA. `XY_(3)`B. `X_(3)Y`C. `XY`D. `XY_(2)`

A compound formed by elements A and B crystallises in cubic structure in which A atoms are at the corners of the cube while B atoms are at the centre of cubic. Formula of the compound isA. ABB. `AB_(2)`C. `A_(2)B`D. `AB_(4)`

A compound contains two types of atoms X and Y. it crystallises in a cubic lattice with atoms X at the corners of the unit cell and atoms Y at the body centre. The simplest possible formula of this compound isA. `X_(8)Y`B. `X_(2)Y`C. XYD. `XY_(8)`

The volume of atom present in a face-centred cubic unit cell of a metal (`r` is atomic radius ) isA. `(20)/(3)pir^(3)`B. `(24)/(3)pir^(3)`C. `(12)/(3)pir^(3)`D. `(16)/(3)pir^(3)`

The molecule having three fold axis of symmetry is :A. `NH_(3)`B. `C_(2)H_(4)`C. `CO_(2)`D. `SO_(2)`

Which of the crystal systems has all the axial angles equal but not equal to `90^(@)`?A. CubicB. TetragonalC. OrthorhombicD. Rhombohedral

Crystal systems in which no two axial lengths are equal areA. TetragonalB. OrthorhombicC. MonoclinicD. Triclinic

Which of the crystal systems have all the axial distances (or edge lengths )equal?A. Cube and rhombohedralB. Cubic and hexagonalC. Cubic and tetragonalD. Only cubic

The crystal system without any element of symmetry isA. monoclinicB. hexagonalC. triclinicD. cubic

A certain crystal has (i) density = `0.456 cm^(-3)` , (ii) a fourfold axis of symmetry and (iii) 4 molecules per unit cell. Side lengths of the unit cell are a = b = 658 pm and c = 593 pm. Calculate the molar mass in g `mol^(-1)`.A. `16.20`B. `17.62`C. `19.25`D. `23`

The presence of F-centres in a crystal makes itA. conductingB. colourlessC. colouredD. None of these

What are F-centres in ionic crystals ? Why are crystals having F-centres are paramagnetic in nature.A. lattice sites containing electronsB. intersitial sites containing electronsC. lattice sites that are vacantD. intertitial sites containing cations

Which of the following compounds is metallic and paramagnetic ?A. `T_(i)O_(2)`B. `CrO_(2)`C. `VO_(2)`D. `MnO_(2)`

why are liquids and gases categorised as fuids ?

In an fcc unit cell, atoms are numbered as shown below The atoms not rouching each other are (Atom numbered `3` is face center of front face)A. 3 and 4B. 1 and 3C. 1 and 2D. 2 and 4

The radius of an atom of an element is `500` pm. If it crystallizes as a face-centred cubic lattice, what is the length of the side of the unit cell?

Sodium has a `bc c` structure with nearest neighbour distance of `365.9` pm. Calculate its density. (Atomic mass of sodium `= 23`)

Sodium has a `bc c` structure with nearest neighbour distance of `365.9` pm. Calculate its density. (Atomic mass of sodium `= 23`)A. `1.5g//cm^(3)`B. `3g//cm^(3)`C. `4g//cm^(3)`D. `5g//cm^(3)`

In a solid lattice the cation has left a lattice sirte and is located at an interstital position , the lattice defect isA. Interstitial defectB. velency defectC. Frenkel defectD. Schottky defect

In a solid lattice the cation has left a lattice sirte and is located at an interstital position , the lattice defect isA. Interstitial defectB. Vacancy defectC. Frenkel defectD. Schottky defect

In `AgCl`, the `Ag^(o+)` ions are deisplaced from their lattice position to an interstitial position. Such a defect is calledA. Schottky defectB. Frenkel defectC. Wadsley defectD. Colour centre

In a solid lattice, the cation has left a lattice site and is located on interstitial position. The lattice defect isA. n-typeB. p-typeC. Frenkel defectD. schottky defect

What are f-centers ?

Which of the following expression is correct in case of a CsCl unit cell (edge length, a)?A. `r_(c)+r_(a)=a`B. `r_(c)+r_(a)=a//sqrt2`C. `r_(c)+r_(a)=sqrt3a//2`D. `r_(c)+r_(a)=a//2`

Give reason: (i) In stochiometric defects, NaCl exhibits schottky defect and not Frenkel defect. (ii) Silicon on doping with phosphorus forms n-type semiconductor . (iii) Ferrimagnetic substances show better magnetisation than antiferromagnetic substences.