Title Chemistry ÔÇó Final Step-B ÔÇó VMC.pdf ✅

Vidyamandir Classes VMC | Final Step | Part B 1 Class XII | Chemistry Final Step - B | Chemistry The Solid State CHOOSE THE CORRECT ALTERNATIVE. ONLY ONE CHOICE IS CORRECT. HOWEVER, QUESTIONS MARKED ‘*’ MAY HAVE MORE THAN ONE CORRECT OPTION. 1. Which of the following is not a characteristic of a crystalline solid ? (A) Definite and characteristic heat of fusion (B) Isotropic nature (C) A regular periodically repeated pattern of arrangement of constituent particles in the entire crystal (D) A true solid 2. Which of the following is an amorphous solid ? (A) Graphite (C) (B) Quartz glass (SiO2) (C) Chrome alum (D) Silicon carbide (SiC) 3. Which of the following arrangements shows schematic alignment of magnetic moments of anti- ferromagnetic substances ? (A) (B) (C) (D) 4. Which of the following is true about the value of refractive index of quartz glass ? (A) Same in all directions (B) Different in different directions (C) Cannot be measured (D) Always zero 5. Iodine molecules are held in the crystal lattice by ___________. (A) London forces (B) Dipole-dipole interactions (C) Covalent bonds (D) Coulombic forces *6. Which of the following is a network solid ? (A) Graphite (B) 2 I (C) Diamond (D) H O2 (Ice) 7. Which of the following oxide behaves as conductor or insulator depending upon temperature ? (A) CaO (B) SiO2 (C) Ti2O3 (D) MgO 8. The lattice site in a pure crystal cannot be occupied by _________. (A) Molecule (B) Ion (C) Electron (D) Atom 9. Schottky defect is observed in crystals when _________. (A) Some cations move from their lattice site to interstitial sites (B) Cations and anions are missing from the lattice in stoichiometric ratio (C) Some lattice sites are occupied by electrons (D) Some impurity is present in the lattice 10. Which of the following is true about the charge acquired by p-type semiconductor ? (A) Positive (B) Neutral (C) Negative (D) Depends on concentration of p impurity 11. The total number of tetrahedral voids in the face centred cubic unit cell is ________. (A) 6 (B) 8 (C) 10 (D) 12
Vidyamandir Classes VMC | Final Step | Part B 2 Class XII | Chemistry *12. Which of the following point defects are shown by AgBr(s) crystals ? (A) Schottky defect (B) Frenkel defect (C) Metal excess defect (D) Metal deficiency defect 13. In which pair most efficient packing is present ? (A) hcp and bcc (B) hcp and ccp (C) bcc and ccp (D) bcc and simple cubic cell 14. The percentage of empty space in a body centred cubic arrangement is _________. (A) 74 (B) 68 (C) 32 (D) 26 *15. Which of the following statement is(are) true about the hexagonal close packing ? (A) The coordination number is 12 (B) It has 74% packing efficiency (C) Tetrahedral voids of the second layer are covered by the sphere of the third layer (D) In this arrangement spheres of the fourth layer are exactly aliened with those of the first layer *16. In which of the following structures coordination number for cations and anions in the packed structure will be same? (A) Cl ion form fcc lattice and Na ions occupy all octahedral voids of the unit cell (B) 2 Ca  ions form fcc lattice and F  ions occupy all the eight tetrahedral voids of the unit cell (C) 2 O  ions form fcc lattice and Na ions occupy all the eight tetrahedral voids of the unit cell (D) 2 S  ions form fcc lattice and 2 Zn  ions go into alternate tetrahedral voids of the unit cell 17. What is the coordination number in a square close packed structure in two dimensions ? (A) 2 (B) 3 (C) 4 (D) 6 18. Which kind of defects are introduced by doping in semiconductor materials ? (A) Dislocation defect (B) Schottky defect (C) Frenkel defects (D) Electronic defects 19. Silicon doped with electron-rich impurity forms _________. (A) p-type semiconductor (B) n-type semiconductor (C) Intrinsic semiconductor (D) Insulator *20. Which of the following statement is(are) true ? (A) Paramagnetic substances are weakly attracted by magnetic field. (B) Ferromagnetic substances cannot be magnetised permanently. (C) The domains in antiferromagnetic substances are oppositely oriented with respect to each other. (D) Pairing of electrons cancels their magnetic moment in the diamagnetic substances. *21. Which of the following statement is(are) true about the ionic solids ? (A) Bigger ions form the close packed structure (B) Smaller ions occupy either the tetrahedral or the octahedral voids depending upon their size (C) Occupation of all the voids is not necessary (D) The fraction of octahedral or tetrahedral voids occupied depends upon the radii of the ions occupying the voids 22. 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 field (B) All the domains get oriented in the direction opposite to the direction of magnetic field (C) Domains get oriented randomly (D) Domains are not affected by magnetic field
Vidyamandir Classes VMC | Final Step | Part B 3 Class XII | Chemistry 23. Which of the following defects is also known as dislocation defect ? (A) Frenkel defect (B) Schottky defect (C) Non-stoichimetric defect (D) Simple interstitial defect 24. In the cubic close packing, the unit cell has ____________. (A) 4 tetrahedral voids each of which is shared by four adjacent unit cells (B) 4 tetrahedral voids within the unit cell (C) 8 tetrahedral voids each of the which is shared by four adjacent unit cells (D) 8 tetrahedral voids within the unit cells 25. The edge lengths of the unit cells in terms of the radius of spheres constituting fcc, bcc and simple cubic unit cell respectively ________. (A) 4r 2 2r, , 2r 3 (B) 4r , 2 2r, 2r 3 (C) 4r 2r, 2 2r, 3 (D) 4r 2r, , 2 2r 3 26. CsCl crystallises in body centered cubic lattice. If ‘a’ its edge length, then which of the following expressions is correct? (A) Cs Cl r r 3a     (B) Cs Cl r r 3a 2     (C) Cs Cl r r 3a 2     (D) Cs Cl r r 3a     27. Experimentally, it was found that a metal oxide has formula M0.98O. Metal M, present as 2 M  and 3 M  in its oxide. Percentage of the metal which exists as 3 M  would be : (A) 7.01% (B) 4.08% (C) 6.05% (D) 5.08% 28. Lithium forms body-centred cubic structure. The length of the side of its unit cell is 351 pm. Atomic radius of the lithium will be : (A) 75 pm (B) 300 pm (C) 240 pm (D) 152 pm 29. In a face-centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centred positions. If one atom of B is missing from one of the face points, the formula of the compound is : (A) A2B (B) AB2 (C) AB (D) A2B5 [30. How many unit cells are present in a cube shaped ideal crystal of NaCl of mass 1.00 g? [Atomic mass : Na = 23, Cl = 35.5] (A) 21 2.57 10  (B) 21 5.14 10  (C) 21 1.28 10  (D) 21 1.71 10  31. The edge length of a face centred cubic cell of an ionic substance is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is : (A) 288 pm (B) 398 pm (C) 618 pm (D) 144 pm 32. Percentage of free space in cubic close packed structure and in body centred packed structure are respectively : (A) 30% and 26% (B) 26% and32% (C) 32% and 48% (D) 48% and 26% 33. Number of atoms in the unit cell of Na (bcc type crystal) and Mg (fcc type crystal) are, respectively : (A) 4, 4 (B) 4, 2 (C) 2, 4 (D) 1, 1 34. In a compound, atoms of element Y form ccp lattice and those of element X occupy 2/3rd of tetrahedral voids. The formula of the compound will be : (A) X Y4 3 (B) X Y2 3 (C) X Y2 (D) X Y3 4 35. Total volume of atoms present in a face-centred cubic unit cell of a metal is (r is atomic radius) : (A) 3 20 r 3  (B) 3 24 r 3  (C) 3 12 r 3  (D) 3 16 r 3  36. An ionic compound has a unit cell consisting of A ions at the corners of a cube and B ions on the centres of the faces of the cube. The empirical formula for this compound would be : (A) A B3 (B) AB3 (C) A B2 (D) AB
Vidyamandir Classes VMC | Final Step | Part B 4 Class XII | Chemistry 37 What type of crystal defect is indicated in the diagram shown below? (A) Frenkel defect (B) Schottky defect (C) Interstitial defect (D) Frenkel and Schottky defects 38. The vacant space in BCC lattice unit cell is : (A) 48 % (B) 23 % (C) 32 % (D) 26 % 39. If a is the length of the side of a cube, the distance between the body centered atom and one corner atom in the cube will be : (A) 2 a 3 (B) 4 a 3 (C) 3 a 4 (D) 3 a 2 40. The number of carbon atoms per unit cell of diamond unit cell is : (A) 6 (B) 1 (C) 4 (D) 8 41. The number of octahedral void(s) per atom present in a cubic close-packed structure is : (A) 1 (B) 3 (C) 2 (D) 4 42. Structure of mixed oxide is cubic closed packed (ccp). The cubic unit cell of mixed oxide is composed of oxide ions. One fourth of the tetrahedral voids are occupied by divalent metal A and the octahedral voids are occupied by a monovalent metal B. The formula of the oxide is : (A) ABO2 (B) A2BO2 (C) A2B2O4 (D) AB2O2 43. Which of the following statement is not correct ? (A) The number of carbon atoms in unit cell of diamond is 8 (B) The number of Bravais lattices in which a crystal can be categorized is 14 (C) The fraction of the total volume occupied by the atoms in a primitive cell is 0.48 (D) Molecular solids are generally volatile 44. If ‘a’ stands for the edge length of the cubic systems: simple cubic, body centred cubic and face centred cubic, then the ratio of radii of the spheres in these systems will be respectively : (A) 1 3 2 a : a : a 2 2 2 (B) 1a : 3a : 2 a (C) 1 3 1 a : a : a 2 4 2 2 (D) 1 1 a : 3a : a 2 2 45. The appearance of colour in solid alkali metal halides is generally due to : (A) interstitial positions (B) F-centres (C) Schottky defect (D) Frenkel defect 46. If a solid A B Θ having ZnS structure is heated so that the ions along two of the axis passing through the face center particles are lost and bivalent ion (Z) enters here to maintain the electrical neutrality, so that the new formula unit becomes A B Z , x y c Report the value of x y c.   47. Metal M of radius 50 nm is crystallized in FCC type and made cubical crystal such that face of unit cells aligned with face of cubical crystal. If the total number of metal atoms of M at all faces of cubical crystal is 30 6 10 ,  then the area of one face of cubical crystal is 16 2 A 10 m .  Find the value of A. 48. 2 O  ions are arranged in ccp in a spinel structure. 2 A  ions occupy 1/8 of TVs and B  ions occupy half of OV. The void volume of unit cell = 0.11 A. Find the value of A.