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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.
| 1601. |
Assertion : The number of tetrahedral voids is double the number of octahedral voids Reason : The size of the tetrhedral voids is half of that of the ochedral voidA. 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 `r_(0) = 0.414 r_("atoms"), r_(0) = 0.732 r_("atoms")` |
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| 1602. |
why is Fe0(s) not formed in stoichiometric compostion ? |
| Answer» in the crystals of FeO some of the `Fe^(2+)` cations are replaced by `Fe^(3+)` ions three `fe^(2+)` ions are repllaced by two `Fe^(3+)` ion to make up the loss of positive chaarge Eventually three would be less amount of metal as comparition | |
| 1603. |
why is ` Fe0(s)` not formed in stoichiometric compostion ? |
| Answer» The chemical formula suggests a stoichiometric composition for the metal oxide )FeO). However, it is found to have compposition of `Fe_(0.95)O`. This means that Fe and O are not in stoichiometric proportions. In fact in the cystal lattice of ferrous oxide (FeO), some `Fe^(2+)` ions are missing and the loss of positive charge is made up by some `Fe^(3+)` ions. Since lesser number of `Fe^(3+)` ions are needed to maintain the electrical neutrality of the lattice, this shows that FeO is not formed in stoichiometric composition. | |
| 1604. |
In solid oxide are arranged in cup .One - sixth of tetrabedral voids are occupied by cation A which one third of octahedral voids are occupied by cation `B` .What is the formula of compound ?A. `AB_(2)O`B. `ABO_(3)`C. `A_(2)B_(3)O`D. `A_(3)B_(2)O` |
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Answer» Correct Answer - b Suppose `O^(2) `ions `+n`, octabedral voids interecdral voids ` = 2n,cation A = (1)/(6) xx 2n = (n)/(3)` `Cation B = (1)/(3) xx n = (n)/(3)` `Ratio - A: B: O^(2)` `= (n)/(3) (n)/(3) :n` Formulas`ABO_(3)` |
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| 1605. |
Assertion : The octahedral viods have double the size of the tetrabedral voids in a crystal Reason: The number of tetrahedral voids is double the number of octabehedral voids is a crystalA. 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 - d Correct assertion Octadudral void are large in size than tetrahedral voids but not double in size. Reason is correct. |
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| 1606. |
A face-centred cubic element (atomic mass `60`) has a cell edge of `400` pm. What is its density? |
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Answer» Correct Answer - `6.23g cm^(-3);` |
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| 1607. |
A solid has a structure in which `W` atoms are located at the corners of a cubic lattice, `O` atom at the centre of edges, and `Na` atom at the centre of the cube. The formula for the compound isA. `NaWO_(2)`B. `NaWO_(3)`C. `Na_(2)WO_(3)`D. `NaWO_(4)` |
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Answer» Correct Answer - B In a unit cell, W atoms at the corner `=(1)/(8)xx8=1` O atoms at the centre of edges `=(1)/(4)xx12=3` Na otoms at the centre of the cube = 1 `W:O:Na=1:3:1` . Hence formula is `NaWO_(3)` . |
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| 1608. |
An element occurs in the body centred cubic alttic with cell edge of 300 pm. The density of the element is `8.0 g//cm^(3)`. Answer the following the distance fo closest approach between the two atoms of the element in the lattics isA. 260 pmB. 300 pmC. 600 pmD. 150 pm |
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Answer» Correct Answer - A Distance of closest approch in bcc `=(sqrt(3)a)/(2)` `=(sqrt(3)x300)/(2)=260` |
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| 1609. |
An element occurs in the body centred cubic alttic with cell edge of 300 pm. The density of the element is `8.0 g//cm^(3)`. Answer the following the atomic mass of the element isA. 65B. 60C. 52D. 80 |
| Answer» Correct Answer - A | |
| 1610. |
which of the following solids is not an electrical conductor ? (a) Mg(s) (b) TiO(s) ( c) `I_(2)(s)` (d) `H_(2)O(s)`A. (A) onlyB. (B) onlyC. (C) and (D)D. (B), (C) and (D). |
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Answer» Correct Answer - C Iodine `(I_(2))` is a molecular solid while ice `(H_(2)O)` is a hydrogen bonded solid. Both of them are not good conductors of electricity. |
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| 1611. |
Which of the following solids is not an electrical conductor ? `{:("(A) Mg(s)", " (B) TiO (S)"),("(C)"I_(2)"(s)","(D)"H_(2)O "(S)"):}`A. (A) onlyB. (B) onlyC. © and (D)D. (B), (C ) and (D) |
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Answer» Correct Answer - A |
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| 1612. |
An element occurs in the body centred cubic alttic with cell edge of 300 pm. The density of the element is `8.0 g//cm^(3)`. Answer the following . the number of nearest neithbours and the next nearbours are respectively.A. 4 and 6B. 4 and 8C. 8 and 8D. 8 and 6 |
| Answer» Correct Answer - D | |
| 1613. |
In solid oxide are arranged in ccp .One - sixth of tetrabedral voids are occupied by cation A which one third of octahedral voids are occupied by cation `B` .What is the formula of compound ?A. `A_(2)BO_(3)`B. `ABO_(3)`C. `AB_(2)O_(3)`D. `A_(2)B_(2)O_(3)` |
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Answer» Correct Answer - B Suppose `O^(2-)` ions = n . Then octahedral voids = n, tetrahedral voids = 2 n Cations A present `=(1)/(6)xx2n=(n)/(3)` . Cations B present `=(1)/(3)xxn=(n)/(3)`. `:.` Ratio `A:B:O^(2-)=(n)/(3):(n)/(3):n=1:1:3` . Hence, , formula is `ABC_(3)` |
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| 1614. |
which of the following solids is not an electrical conductor ? (a) Mg(s) (b) TiO(s) ( c) `I_(2)(s)` (d) `H_(2)O(s)`A. only 1B. only 2C. 3 and 4D. 2,3 and 4 |
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Answer» Correct Answer - C iodine is a non- polar molecular solid iodine moleculas are held together by london force or dispersion force , this is soft and non - conductor fo electricity . Water is a hydrogen bonded molecular solid in which H and O are held together by to non - ionic nature , they are not electrical conductor. |
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| 1615. |
In zinc blende structure anions are arranged in ccp and cations are present in the tetrachedral voids and only half the tetrahedral voids are occupied, the coordination numbers of cation and anion are respectivelyA. 4 and 8B. 4 and 4C. 8 and 4D. 8 and 6 |
| Answer» Correct Answer - B | |
| 1616. |
In zinc blende structure anions are arranged in ccp and cations are present in the tetrachedral voids and only half the tetrahedral voids are occupied, for this type of structure , radius ratio r/r should be in the rangeA. 0.225 - 0.414B. 0.155 - 0.225C. 0.414 - 0. 732D. 0.732-1 |
| Answer» Correct Answer - A | |
| 1617. |
Iron crystalizes in two bcc lattices, the `alpha-` from below `910^(@)` and the `gamma`-form above `1400^(@)`C, and in an fcc `gamma`-atom between these two temperatures. `gamma`-form dissolve appreciable amounts of carbon and occupies ______ in fcc.A. T.V.B. O.V.C. Alternative T.V.D. cubic void |
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Answer» Correct Answer - B Carbon is too big to occupy either type of void in a bcc structure but can fit with in an OV of an fcc structure. (i.e., `gamma`-form) |
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| 1618. |
Which of the following FCC structure contains cations in alternate tetrahedral voids?A. NaClB. ZnSC. `Na_(2) O`D. `CaF_(2)` |
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Answer» Correct Answer - B |
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| 1619. |
Which of the following fc c structure contains cations in alternate tetrahedral voids ?A. `NaCI`B. `ZnS`C. `Na_(2)O`D. `CaF_(2)` |
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Answer» Correct Answer - B |
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| 1620. |
A perfect crystal of silicon (fig) is doped with some elements as given in the options , which of these options shows n- type semiconductors ? A. B. C. D. |
| Answer» Correct Answer - A::C | |
| 1621. |
How do the electrical conductivity and resistivity of metallic conductors, semi-conductors, and super conductors vary with temperature ? |
| Answer» It decreases with the rise in temperature. | |
| 1622. |
The electrical conductivity of a metal decreases with rise in temperature while that of semi-conductor increases. Justify. |
| Answer» The electrical conductivity of a metal decreases with the rise in temperature because the positively charged kernels present in the electron sea also acquire mobility and obstruct the movement of valence electrons responsible for conductivity. In semi-conductros, the electrical conductivity increases because more electrons are in a position to move from valence band to the conduction band since there is only a small energy gap. | |
| 1623. |
Electrical conductivity of semiconductor A… with rise in temperature . Here , A refers toA. IncreasesB. DecreasesC. Both a and bD. Remains unchanged |
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Answer» Correct Answer - A Electrical conductivity of semiconductors increases with rise in temperature so that electrons can jump to the conduction band. |
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| 1624. |
The electrical conductivity of a metal decreases with rise in temperature while that of a semiconductor increases . Explain. |
| Answer» In case of metals, with increase of temperature the kernals start vibrating and thus offer resistance of the flow of electrons . Hence, conductivity decreases. In case of semiconductors , with increase of temperature more electrons can shift from valance band to conduction band. Hence, conductivity increases. | |
| 1625. |
Assertion (A) : The electrical conductivity of a semiconductor increases with increase in temperature. Reason (R ) : With increase in temperature, large number of electrons from the valence band can jump to the conduction band.A. If both the statement are TRUE and STATEMENT -2 is the correct explanation of STATEMENT -1B. If both the statement are TRUE and STATEMENT -2 is NOT the correct explanation of STATEMENT -1C. If STATEMENT -1 is the correcct and TRUE and STATEMENT -2 is FALSED. If STATEMENT -1 is the correcct and FALSE and STATEMENT -2 is TRUE |
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Answer» Correct Answer - A |
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| 1626. |
Assertion : Diamond is a precious stone Reason : carbon atomic are tetrahedrally arranged in dimondA. 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 - b It is true in the diamond structure , carbon atoms are arrangement tetrahedral `(sp^(3)` hybridized) but it is not the correct explanation of assertion |
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| 1627. |
No crystal is found to be prefect at room temperature. The defects present in the crystals can be stoichimetric or non-stoichiometric. Due to non-stoichimetric defects, the formula of the ionic compound is different from the ideal formula. For example , the ideal formula of ferrous oxide should be FeO but actually in one sample , it was found to be ` Fe_(0.93)`O. This is because the crystal may have some ferric ions in place of ferrous ions. These defects change the propeties of the crystals. In some cases, defects are introduced to have crystals of desired properties as required in the field of electronics. Doping of elments of Group 14 with those of Group 13 or 15 is most common. In ionic compounds, usually impurities are introduced in which the cation has higher valency than the cation of the parent crystal, e.g, ` SrCl_(2)` into NaCl. which one of the following defects does not affect the density of the crystal ?A. Schottky defectB. Interstitial defectC. Frenkel defectD. Both in (b) and (c ) |
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Answer» Correct Answer - c Frenkel defect does not affect the density of the crystal because cations are missing from lattice sites and occupy intersitial sites. |
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| 1628. |
In terms of band theory , what is the differnec (i) Between a conductor and an insulator. (ii) between a conductor and a semicondutor ? |
| Answer» (i) The energy gap betweeen the valence band and conduction band in an insulation is very large wheras in a conductor , the energy gap is very small or there is overlapping between valance band and conduction band. (ii) In a conductor, there is very small, energy gap or there is overlapping between valance band and conduction band but in a semiconductor, there is always a small energy between them. | |
| 1629. |
When a substance conducts elecricity without any resistance, it is called a …….. . |
| Answer» Correct Answer - Supercondutor | |
| 1630. |
Assertion : Diamond is a precious stone Reason : carbon atomic are tetrahedrally arranged in dimondA. 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 the assertion and reason both are false.D. If assertion is false but reason is true. |
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Answer» Correct Answer - B It is true that in the diamond strcutre, carbon atoms are arranged tetrahedrally (`sp^(3)` hybridized) but it is not the correct explanation of assertion. |
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| 1631. |
Assertion (A) : The electrical conductivity of a semiconductor increases with increase in temperature. Reason (R ) : With increase in temperature, large number of electrons from the valence band can jump to the conduction band.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. |
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Answer» Correct Answer - A In case of semiconductors, the gap between valence band and the conduction band is small and therefore some of the electrons may jump from valence band to conduction band and thus on increasing temperature conductivity is also increased. |
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| 1632. |
Why is glass of window panes of very old builidings found to be thicker at the bottom than as the top and why is it milky ? |
| Answer» Glass is an amorphous solid which is a supercooled liqquid of high viscosity ans hence possessses fluidity. Due to this property it is thicker at the bottom than at the top. Mikiness of glass is due to the fact that it undergoes heating during the day and cooling at night i.e. annealisg over a number of years. As a result , it acquires some cystalline character. | |
| 1633. |
Assertion: Crystalline solids have short range order. Reason: Amorphous solids have long range order.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 assertion is false but reason is true. |
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Answer» Correct Answer - D Crystalline solids have regular arrangement of constituent particles and are anisotropic whereas amorphous solids have no regular arrangement and are isotropic. |
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| 1634. |
A liquid which is permanently supercooled is frequently called a ……….. . |
| Answer» Correct Answer - Glass | |
| 1635. |
Why is glass considered a supercooled liquid ? |
| Answer» Liquids have the characteristic property i.e., the tendency to flow . Glass also shows this property , though it flows very slowly . Glass panes fixed to windows or doors of old buildings are invariably found to be slightly thicker at the bottom than the top . This is because the glass flows down very slowly and makes the bottom portion slightly thicker . Therefore , glass is considered as a supercooled liquid . | |
| 1636. |
Why is glass considered a supercooled liquid? |
| Answer» Glass is considered to be super cooled liquid because it shows some of the characteristics of liquids, though it is an amophous solid. For example, it is slightly thicker at the bottom. This can be possible only if it has flown like liquid, though very slowly. | |
| 1637. |
Write the coordination number of each ion in the following crystals . (i) NaCl (ii) CsCl (iii) ZnS (iv) ` CaF_(2)` ( v) ` Na_(2)O` |
| Answer» `Na^(+) = 6, Cl^(-) =6 , (ii) Cs^(+) = 8, Cl^(-) = 8 (iii) Zn^(2+) = 4, S^(2-) = 4 (iv) Ca^(2+) = 8, F^(-) = 4 , (v) Na^(+) = 4, O^(2-) = 8 ` | |
| 1638. |
Why stoichiometric defects are also called intrinsic defects ? |
| Answer» Stoichiometric defects are so called because they do not alter the stoichiometry of the crystal ( Schottky defect and Frenkel defect). They are called intrinsic defects beacause it is due to the deviation from regular arrangement of atoms or ions within the crystal and no external substance is added. | |
| 1639. |
Gold (atomic radius = 0.144 nm) crystallises in a face centred unit cell. What is the length of the side of the cell. |
| Answer» For FCC , ` a = 2 sqrt2 r = 2 xx 1.414 xx 0.144 nm = 0.407 nm ` ] | |
| 1640. |
How can a material be made amorphous ? Give an example of supercooled liquid. |
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Answer» By melting the material and then cooling it rapidly. Glass. |
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| 1641. |
Although amorphous solids do not posses the long range order of crystals, they do have ……… just as liquids do. |
| Answer» Correct Answer - Some local or short range order | |
| 1642. |
If `NaCI` is droped with `10^(-4) "mole"% of SrCI_(2)` then number of cationic vacancies will beA. `6.02 xx 10^(16) mol^(-1)`B. `6.02 xx 10^(17) mol^(-1)`C. `6.02 xx 10^(14) mol^(-1)`D. `6.02 xx 10^(15) mol^(-1)` |
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Answer» Correct Answer - b What `SrCI_(2)` doped with `NaCI` One `Sr^(2+)` replaces two `Na^(+)` ions and occupies a lattice point and produces one cation vacancy `100 mol NaCI `will have `10^(-4)` cation vacancy ` 1 mol = (10^(4))/(100) = 10^(6) mol` Number of cation vacancies `= 10^(-6) xx 6.02 xx 10^(23)` `= 6.02 xx 10^(17)` atoms |
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| 1643. |
What type of defect can arise when a solid is heated ? Physical property is affected by it and in what why ? |
| Answer» When a solid is heated , a vacancy is created in the crystal . On heating , some of the lattice sites are vacant and the density of the solid decreases as the number of ions per unit volume decreases. | |
| 1644. |
Why the defects of the crystalline solides are called thermodynamic defects ? |
| Answer» There is perfect arrangement of the constituent particels only at 0k , As the rtemperature increases (say upto room temperature ) , The chance that a lattice site may be unoccupied by an ion increases. As the number of defects increases with temperature ,the defects are called themodynamic defects. | |
| 1645. |
What is meant by co-ordintion number (C.N.) ? |
| Answer» Co-ordination number (C.N.) of particle (atom/ion) is the number of nearest neighbours in its contact. | |
| 1646. |
Why the defects of the crystalline solids are called thermodynamic defects? |
| Answer» There is a perfect arrangement of constituent particles in a crystalline solid at 0K. As the temperature increases, the particles are likely to leave their lattice site and may occupy positions elsewhere. In other words, the defects are likely to increase with the rise in temperature. Therefore, these are called thermodynamic defects. | |
| 1647. |
Ionic solids conduct electrical insulator in solid as well as in molten state but not in solid state. Explain |
| Answer» The conductivity of ionic solids is due to the ionic mobility which is present only in the molten state and not in the solid state. | |
| 1648. |
The correct statement regarding defects in crystalline solids isA. Frenkel defect is a dislocation defectB. Frenkel defect is found in halids of alkaline metalsC. Schottky defects have no effect on the density of crystalline solidsD. Frenkel defects decrease the density of crystalline solids |
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Answer» Correct Answer - d Frenkel defect is a dislocation defect as some cations are dislocated from lattice sites and occupy intersitial sites. |
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| 1649. |
Define the terms (i) Crystalline solids (ii) Frenkel defects (iii) n-type semi-conductors. |
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Answer» (i) Crystalline solids (ii) Frenkel Defects (iii) n-type semi-conductor |
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| 1650. |
Which of the following shows ferrimagnetism?A. `TiO_(2)`B. `CrO_(2)`C. `MnO`D. `Fe_(3)O_(4)` |
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Answer» Correct Answer - 4 Ferrimagnetisms is observed when the magnetic moments of the domains in the substance are aligned (in an external magnetic field) in parallel and antiparalle directions in unequal numbers `Fe_(3)O_(4)` (magnetite) and ferrites like `MgFeO_(4)` and `ZnFe_(2)O_(4)` are example of such substances. |
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