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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.
| 1301. |
Explain why ionic solids are hard and brittle . |
| Answer» In ionic solids the formation of solid compound is due to the arrangement of cations and anions bound by strong coloumbic force i.e., electro static force . So ionic solids are hard and brittle in nature . These have high melting and boilig point . | |
| 1302. |
What type of solids are electrical conductors, malleable or ductile? |
| Answer» Metallic solids exhibit these characteristics. Their atoms are linked to one another by metallic bonds. | |
| 1303. |
Which of the following is/are ture about HCP and CCP lattice?A. Number of tetrahedral voids are twice of octahedral holesB. 12 tetrahedral and 6 octahedral voids are present in one HCP unit cellC. C.N. of HCP unit cell is 12D. If atom of tetrahedral voids displace into octahedral voids then it is Schootky defect |
| Answer» Correct Answer - A::B::C | |
| 1304. |
The density of `KBr` is `2.75 gm//c c` length of the unit cell is `654pm` ( atomic masses of `K=38,Br=80)` then what is true about the predicted nature of the solidA. Solid has F.C.C structure with co`-` ordination number `=6`B. Solid has simple cubic structure with co`-` ordination number `=4`C. Solid has F.C.C. structure with co`-` ordination numbers `-1`D. None of these |
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Answer» Correct Answer - 1 `2.75=(Zxx118)/((6.54xx10^(-8))^(2)xx6.023xx10^(23))" "rArr" "Z=4(` foc with NaCl type structure`)` |
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| 1305. |
Spinel is the mineral with the formula…….. |
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Answer» Correct Answer - ` 6(r_(+)//r_(-) = 0.44` which lies in the range ( 0.414 - 0.732) |
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| 1306. |
Calculate the void space in a primitive unit cell and also the fraction of the total volume occupied .A. 52B. 48C. 74D. 26 |
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Answer» Correct Answer - B a=4rVolume of the cube `=a^(3)=(2r)^(3)=8r^(3)` Packing fraction `=("volume of one atom")/("volume of the cube")` `(((4)/(3)pir^(3)))/(8r^(3))=(pi)/(6)=0.52` `therefore` Void fraction `=1-0.52=0.48` `therefore` Void space =48% |
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| 1307. |
The strcture of `MgO` is similar to NaCl. What is the co- ordination number of `Mg`? |
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Answer» Correct Answer - 6 |
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| 1308. |
What is the condition number of an atom for an element crystallizing with a cubic lattice? Calculate the corresponding coordination number for the simple, fcc and bcc lattics:A. 12sc, 12fcc, 8bc cB. 6sc, 14fcc, 8bc cC. 8sc, 12fcc, 6bc cD. sc, 12fcc, 8bc c |
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Answer» Correct Answer - D |
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| 1309. |
Which of the following layering pattern will have a void fraction of 0.260?A. ABCCBAABCB. ABBAABBAC. ABAABCABAD. ABCAABCA |
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Answer» Correct Answer - C |
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| 1310. |
Find the distance ( in pm) between the body centered atoms one corner atom in an element `( a = 2.32 "pm")` |
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Answer» Correct Answer - 2 |
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| 1311. |
What types of crystals show pyroelectricity ? |
| Answer» Polar crystals upon heating show pyroelectricity. | |
| 1312. |
Give one example of peizoelectric substance. |
| Answer» Lead zironate (Pb Zr `O_(2)`) | |
| 1313. |
Superconductors are derived from the compounds ofA. p-block elementsB. lanthanidesC. actinidesD. transition elements |
| Answer» Correct Answer - A | |
| 1314. |
Ina crystal of zinc sulphide, zinc occupies tetrahedral voids. What is the coodination number of zinc ? |
| Answer» Correct Answer - 4 | |
| 1315. |
What will happen when a small amount of phosphorus is addded to pure crystal of silicon ? |
| Answer» It will result in the formation of n-type of semi-conductors. | |
| 1316. |
The coordination number of each sphere in hexagonal close packing is …….. While that of body -centred cubic packing is….. |
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Answer» Correct Answer - 26%, 32% |
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| 1317. |
What is the corrdination number of an octahedral voids ? |
| Answer» Correct Answer - six . | |
| 1318. |
Which point defect is observed in a crystal when a vacancy is created by an atom or ion missing from its normal position ? |
| Answer» Correct Answer - Schottky defect | |
| 1319. |
In what way, do Schottky and Frenkel defects differ from each other ? |
| Answer» In the nature of cationic & anionic vacancies | |
| 1320. |
Given packing efficiency and coordination number of the following crystal structres . (a) body centred cubic (b) cubic close packing |
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Answer» (a) packing efficiency of bcc= 68 % , corrdination number = 8 (b) packing efficiency of ccp (fcc) = 74% , coordination number = 12 |
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| 1321. |
Assuming that atoms are touching each other, calcualte the packing efficiency in case of a crystal of simple cubic metal. |
| Answer» Correct Answer - `52.4%` | |
| 1322. |
In which of the following crystals, alternate tetrahedral voids are occupied?A. NaClB. ZnSC. `CaF_(2)`D. `Na_(2)O` |
| Answer» Correct Answer - B | |
| 1323. |
In which of the following crystals, alternate tetrahedral voids are occupied?A. NaClB. ZnSC. `CaF_2`D. `Na_2O` |
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Answer» Correct Answer - B In ZnS structure, sulphide ions occupy all (fcc) lattice points while `Zn^(2+)` ions are present in alternate tetrahedral sites. |
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| 1324. |
Assertion (A) : Covalent crystals have higher melting point. Reason (R ) : Covalent bonds are stronger than ionic bonds.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. |
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Answer» Correct Answer - C Assertion is correct since higher melting points of covalent crystals are due to network structures. Correct (R): Covalent bonds are weaker than ionic bonds. |
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| 1325. |
Statement -1 : Covalent crystals have the highest melting point . Statement 2: Covalent bonds are stronge than ionic bonds.A. Statement 1 is True , Statementy -2 True , Statement -2 is a correct explanation for statement -1 .B. Statement 1 is True , Statement -2 is True , Statement -2 in NOT a correct explanation of statement -1.C. Statement -1 is True , Statement -2 is False.D. Statement -1 is False , Statement -2 is True. |
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Answer» Correct Answer - b Correct Statement-2. Covalent bonds are weaker ionic bonds. (Higher melting points of Covalent are due to net-work structure). |
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| 1326. |
A binary solid `(A^(+)B^(-))` has a ruck salt structure. If the edge length is 400pm and radius of cation is 75pm the radius of anion isA. 100pmB. 125pmC. 250pmD. 325pm |
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Answer» Correct Answer - 2 Edge length `(a)=2(r_(c)+r_(a))` `2r_(a)=a-2r_(c),r_(a)=(a-2r_(c))/(2)` |
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| 1327. |
In which of the following crystals, alternate tetrahedral voids are occupied?A. `NaCI`B. `ZnS`C. `CaF_(2)`D. `Na_(2)O` |
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Answer» Correct Answer - b In `ZnS` structure , sulpahide ions occupy all `FC C` lattice points while `Zn^(2+)` ions are present in ahemate tetrabedral voids. |
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| 1328. |
Which of the following cotains ruck salt struture?A. `SrF_(2)`B. `MgO`C. `Al_(2)O_(2)`D. All |
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Answer» Correct Answer - b `MgO` constant rock cell `(NaCI)` structure. |
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| 1329. |
Structure similqar to zine blebde is found inA. `AgCI`B. `NaCI`C. CuCI`D. TICI` |
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Answer» Correct Answer - c Zine blends `(ZnS)` has `fcc` atructure and is an ionic crystal lattice having `4:4` ions are present co-codination number. |
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| 1330. |
Assertion (A) : Covalent crystals have higher melting point. Reason (R ) : Covalent bonds are stronger than ionic bonds.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true bur reason is falseD. If assertion is false bur reason is true |
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Answer» Correct Answer - c Correct reason covalent bonds are weaker than ions bonds (Higher melting point of covalent crysatl are due to network structure) |
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| 1331. |
In `CsCI` lattice the coordination number of `Cs` ion isA. `2`B. `8`C. `4`D. `12` |
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Answer» Correct Answer - b Each `Cs^(+)` is surronded by eight `CI^(+)` ions in `CsCI` crystal lattice becouse its co- cediretion number is `8:8` |
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| 1332. |
Assertion : `CsCI` has body - centred cunic arrangement Reason: `CsCI` has one and `8 CI^(-)`ion is its unit cellA. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true bur reason is falseD. If assertion is false bur reason is true |
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Answer» Correct Answer - c correct reason `CsCI` has one `Cs` ion one `CI` ion in its unit cell |
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| 1333. |
A molecule `A_(2)B (Mw = 166.4)` occupies triclinic lattice with `a = 5 Å, b = 8 Å`, and `c = 4 Å`,. If the density of `AB_(2)` is `5.2 g cm^(-3)`, the number of molecules present in one unit cell is |
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Answer» Correct Answer - 3 Volume of unit cell `=axxbxxxc` `=5xx10^(-8)xx8xx10^(-8)xx4xx10^(-8)` `=1.6xx10^(-22)cm^(3)` Mass of unit cell `=1.6xx10^(-22)xx5.2` `=8.32xx10^(-22)g` No. of molecules in one unit cell `=(8.32xx10^(-22)xx6xx10^(23))/(166.4)=3` |
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| 1334. |
The ionic radius of `Cl^(-)` ion is `1.81 Å` . The inter-ionic distances of NaCl and NaF are `2.79 Å` respectively. The ionic radiusof `F^(-)` ion will beA. `0.98 Å`B. `0.80 Å`C. `1.33 Å`D. `2.29 Å` |
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Answer» Correct Answer - C `d_(NaCl)=r_(Na).^(+)+r_(Cl-)` `2.79=r_(Na)+1.81` or `r_(Na)+=2.79-1.81 Å =0.98 Å` `d_(NaF)=r_(Na).^(+)+r_(F).^(-)`, i.e., `2.31=0.98+r_(F).-` or `r_(F).- =2.31-0.98=1.33 Å` |
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| 1335. |
Solid `A^(+)B^(-)` has a bcc structure .If the distance of closest apporach between two atoms is 173 pm ,the edge length of the cell is:A. 200 pmB. `sqrt(3)//sqrt(2)` pmC. `142.2` pmD. `sqrt(2)` pm |
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Answer» Correct Answer - A For bcc, d `=(sqrt(3))/(2)a` or `a=(2d)/(sqrt(3))=(2xx173)/(1.732)=200` pm |
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| 1336. |
The edge length of unit cell of a metal `(Mw = 24)` having cubic structure is `4.53 Å`. If the density of metal is `1.74 g cm^(-3)`, the radius of metal is `(N_(A) = 6 xx 10^(23))`A. `180` pmB. `160` pmC. `140` pmD. `190` pm |
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Answer» Correct Answer - B `rho = (Z_(eff) xx Mw)/(.a^(3) xx N_(A))` `1.74 g cm^(-3) = (Z_(eff) xx 24)/((4.53 xx 10^(8))^(3) cm^(3) xx 6 xx 10^(23)"atoms")` `:. Z_(eff) = 4` (fcc structure) For fcc, the radius of atom is. `r = (a)/(2sqrt(2)) = (4.53Å)/(2sqrt(2)) = 1.60Å = 160 "pm"` |
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| 1337. |
The density of an ionic compounds `(Mw = 58.5)` is `2.165 kg m^(-3)` and the edge length of unit cell is `562` pm, then the closest distance between `A^(o+)B^(ɵ)` and `Z_(eff)` of unit cell isA. `281` pm, `4`B. `562` pm, `2`C. `562` pm, `4`D. `281` pm, `2` |
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Answer» Correct Answer - A `rho=(Z_(eff)xxMw)/(a^(3) xx N_(A))` `2.165 kg m^(-3) = (Z_(eff) xx 58.5 xx 10^(-3)kg mol^(-1))/((562 xx 10^(-12))^(3)m^(3) xx 6 xx 10^(23)"atoms")` `:. Z_(eff) = 4` (fcc-type structure). For `fcc`, `d_(A^(o+))-B^(ɵ) = (a)/(2) = (562)/(2) = 281 "pm"` |
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| 1338. |
Assertion : The total number of atoms present in a simle cubic unit cell is one. Reason : Simple cubic unit cell has atoms at its corners, each of which is shared between eight adjacent unit cells.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 . |
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Answer» Correct Answer - b |
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| 1339. |
Match the items given in Column I with the items given in Column II. `{:( " Column I " , " Column II"),( "(i) Mg in solid state" , " (a) p -type semiconductor"),("(ii)" MgCl_(2) " in molten state" , "(b) n-type semiconductor"),(" (iii) Silicon with phosphorus" , "(c) electrolytic conductors ") , (" (iv) Geranium with boron " , " (d) Electronic conductors " ):}` |
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Answer» Correct Answer - ` (i) to c,(ii) to a, (iii) to d, (iv) to b` |
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| 1340. |
Calculate the edge length of the unit cell of sodium chloride given density of NaCI is `2.17 xx 10^(3) kgm^(-3)` and molecular weight `58.5 xx 10^(-3)kg mol^(-1)`. |
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Answer» NaCl is face-centred cubic lattice so that number of NaCl molecules in a unit cell (z) = 4 We know density `d = (zM)/(a^(3)N_(0))` where a = length of the unit cell volume `= a^(3) = (Mz)/(dN_(0)) = (4 xx 58.8 xx 10^(-3))/(2.17 xx 10^(3) xx 6.02 xx 10^(23)) = 1.79 xx 10^(-28) m^(3)` `a = 5.64 xx 10^(-10) m = 5.64 Å = 564` pm |
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| 1341. |
A crystal of KCl containing a small amount of `CaCl_(2)` will haveA. vacant `Cl^(-)` sitesB. vacant `K^(+)` sites and a higher density as compared to pure KClC. vacant `K^(+)` sites and a lower density as compared to pure KClD. `K^(+)` ions in the interstitial sites |
| Answer» Correct Answer - C | |
| 1342. |
If calcium crystallizes in `bc c` arrangement and the radius of `Ca` atom is `96 pm`, then the volume of unit cell of `Ca` isA. `10.9 xx 10^(-36) m^(3)`B. `10.9 xx 10^(-30) m^(3)`C. `21.8 xx 10^(-30) m^(3)`D. `21.8 xx 10^(-36) m^(3)` |
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Answer» Correct Answer - B For bcc latice, `sqrt(3)a = 4R rArr a = (4 xx 96)/(sqrt(3))` pm `= 22.17` pm (where `R` is the radius of `Ca` atom) Volume of unit cell `= a^(3) = (22.17 xx 10^(-12))^(3) = m^(3)` `= 10.9 xx 10^(-30) m^(3)` |
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| 1343. |
`Li` forms a body-centred cubic lattice. If the edge of the cube is `3.5 xx 10^(-10)m` and the density is `5.3 xx 10^(2) kg m^(-3)`, calculate the percentage occupancy of `Li` metal. |
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Answer» `= (Z_(eff) xx Aw)/(N_(A) xx a^(3)) = (2 xx 7 xx 10^(-3))/(6.023 xx 10^(23) xx (3.5 xx 10^(10))^(3))` `= 5.4 xx 10^(2) kg m^(-3)` Percentage occupancy `= (5.3 xx 10^(2))/(5.4 xx 10^(2)) xx 100 = 98%` |
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| 1344. |
`Li` forms a body-centred cubic lattice. If the edge of the cube is `3.5 xx 10^(-10)m` and the density is `5.3 xx 10^(2) kg m^(-3)`, calculate the percentage occupancy of `Li` metal.A. `25.78%`B. `1.54g//cm^(2)`C. `3.4g//c^(3)`D. `5.4g//cm^(3)` |
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Answer» Correct Answer - D We have theoretical density `=(zM)/(NV)=(zM)/(N(a^(3)))` For a b.c.c. lattice`,z=2` and given that `a=3.50xx10^(-10)` and `M=7xx10^(-3)kg//mol e` `d_(cell)=(2xx(7xx10^(-3)))/(6.022xx10^(23)xx(3.50xx10^(-10))^(3))=5.42xx10^(2)kgm^(-3)` |
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| 1345. |
Give an example of 12-16 compound ? |
| Answer» It is a compound formed by the combination of elements of group 12 and group 16. For example, zine sulphide (ZnS). | |
| 1346. |
The size of `Cl^(-)` ion is `1.8Å` . The size of a cation for which a change in coordination just becomes possible from 6 to 8 in an ideal ionic crystal would be `:`A. `0.7452Å`B. `1.3176Å`C. `0.405Å`D. `1.8Å` |
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Answer» Correct Answer - 2 `{:(R R R,,CN),(0.414 le (r_(+))/(r_(-)) lt 0.732,,6),(0.732 le (r_(+))/(r_(-)) lt 1.00,,8):}` Hence use the RR of `0.732` corresponding to the said changeover from CN of 6 to CN of 8. Hence cation size is `0.732xx1.8=1.3176Å` |
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| 1347. |
The ionic radii of `A^(+)` and `B^(-)` ions are `0.98xx10^(-10)m` and `1.81xx10^(-10)m`.The coordination number of each ion in `AB` is :A. `2`B. `6`C. `4`D. `8` |
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Answer» Correct Answer - 2 Let calculate the radius ratio: `(r_(+))/(r_(-))=(0.98xx10^(10)m)/(1.81xx10^(-10)m)=0.541` Since it lies the range `0.414-.732` ,the coordination number of each ion is `6`. |
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| 1348. |
What is the packing fraction in face centred cubic lattice ? |
| Answer» The packing fraction or the volume of occupied space in f.c.c. packing is 0.74 (or `74%`). | |
| 1349. |
For an ionic solid of the genrel formula `AB` and coordination number `6` , the value of the radius ratio will beA. less then `0.225`B. in bwetween `0.225` and `0.732`C. between `0.414` and `0.732`D. greater then `0.732` |
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Answer» Correct Answer - a Ionic solid having `C.N = 6` cations in octabudral hles Hence `0.414 lt((r_(+))/(r_(-)))lt 0.732` |
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| 1350. |
The number of octahedral sites per sphere in fcc structure isA. `1`B. `4`C. `2`D. `8` |
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Answer» Correct Answer - a Number of ncubedral sites = Number in the packing `:.` Number of ocubedral slkites per sphere `= 1` |
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